Method and system for drawing degree of shielding of certain point by mountain based on CAD (Computer Aided Design)

Abstract

The invention discloses a method and system for drawing the shielding degree of a certain point by a mountain based on CAD, and mainly relates to the technical field of mountain photovoltaic and mountain agriculture. Comprising the steps of collecting a standardized contour drawing; defining input parameters for the collected contour line drawing; inputting or specifying parameters of a to-be-measured point, a contour map layer, a contour map, a 1m-height solar ray vector east-west component, a 1m-height solar ray vector south-north component and a terrain clearance; calculating a maximum shielding value and a three-dimensional point at a position where the maximum shielding value is generated; drawing a shielding line and a maximum shielding value character; and turning over the sunlight east and west, and executing the steps again. The method has the beneficial effect that the shielding degree of a certain point on the contour map by the mountain can be quickly drawn in the CAD.

Description

Technical Field

[0001] The present invention relates to the technical fields of mountain photovoltaic and mountain agriculture, and in particular to a method and system for drawing the degree to which a certain point is blocked by a mountain based on CAD. Background Art

[0002] Mountainous terrain is complex and steep. During certain periods of time during the day, large areas may be blocked by high ground and cannot be directly exposed to the sun. When selecting sites for photovoltaic or agricultural projects in mountainous areas, the phenomenon of mountain blocking must be considered. Otherwise, photovoltaic modules or crops may not be able to receive sunlight during periods of good sunlight, resulting in a reduction in power generation and agricultural output, and a waste of resources.

[0003] Taking mountain photovoltaic as an example, the photovoltaic layout location must generally follow the principle that "the photovoltaic modules should not be blocked from 9:00 to 15:00 local time every day in a year". Sometimes the above time interval can be fine-tuned according to the site conditions, and its essence remains unchanged. It has been found through actual operation that the mountain shielding on the winter solstice is the most serious in a year, and the shielding area on the winter solstice almost completely covers any shielding area on non-winter solstice days. Therefore, the mountain shielding on the winter solstice should be considered when deciding the photovoltaic layout area. It has also been found through actual operation that on the winter solstice, under the premise of following the principle that "the photovoltaic modules should not be blocked from 9:00 to 15:00 local time every day in a year", the mountain shielding at 9:00 and 15:00 local time is the most serious, and the shielding area at 9:00 and 15:00 local time almost completely covers any shielding area between 9:00 and 15:00 local time. Therefore, the mountain shielding at 9:00 and 15:00 local time on the winter solstice should be considered when deciding the photovoltaic layout area.

[0004] The light emitted by the sun at a certain place and time can be regarded as a three-dimensional vector. If the latitude of a certain place has been determined, the three-dimensional solar vector of that place at every time and every day of the year can be solved. The solution process is complicated and will not be elaborated here. Flexible use of mainstream sunshine analysis software on the market can directly obtain the three-dimensional value of the solar vector.

[0005] Mountain photovoltaic projects usually require that the bottom edge of the photovoltaic array must be at least several meters above the ground, and the leaves of mountain crops may also be at a certain height from the ground.

[0006] Problems with existing technologies

[0007] 1. The terrain in the mountains is complex and steep. During certain periods of time during the day, large areas may be blocked by high ground and cannot be directly exposed to the sun. When selecting sites for photovoltaic projects or agricultural projects in the mountains, the phenomenon of mountain blocking must be considered. Otherwise, photovoltaic modules or crops may not be able to receive sunlight during periods of good sunlight, resulting in a reduction in power generation and agricultural output, and a waste of resources.

[0008] 2. The contour map is complex and it is difficult to tell with the naked eye which areas are blocked by the mountains. Sometimes when the owners ask why photovoltaic panels or crops are not arranged in certain areas, it is difficult for the designers to answer on the spot in a short time.

[0009] Therefore, there is an urgent need for a method and system for drawing the degree to which a certain point on a contour map is blocked by a mountain based on CAD to solve the above problem. Summary of the invention

[0010] The purpose of the present invention is to provide a method and system for drawing the degree to which a certain point is blocked by a mountain based on CAD, which achieves the effect of quickly drawing the degree to which a certain point on the contour map is blocked by a mountain when the measured point, contour layer, contour map, 1m height sun ray vector east-west component, 1m height sun ray vector north-south component, and height from the ground are input or pointed out.

[0011] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0012] On the one hand, a method for drawing the degree to which a certain point is blocked by a mountain based on CAD is provided, comprising the following steps:

[0013] S1: Collect standardized contour drawings;

[0014] S2: For the collected contour drawings, define the input parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, height above the ground, define the concept of the test line, the test elevation, the three-dimensional intersection, the profile of the mountain to be tested, the test point above the ground, the perihelion, the aphelion, the highest height of the field, the shielding value, the maximum shielding value, the shielding line, and the text of the maximum shielding value;

[0015] S3: Input or specify the parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, and height from the ground;

[0016] S4: Calculate the maximum occlusion value and the three-dimensional point where the maximum occlusion value occurs;

[0017] S5: Draw the occlusion line and the maximum occlusion value text;

[0018] S6: Turn the sunlight from east to west and perform the steps S4 and S5 again.

[0019] Preferably, the collection of standardized contour drawings follows the following principles:

[0020] All contour lines in the drawing must be of polyline type;

[0021] The height of the contour lines in the drawing should be reflected in the elevation parameters of the polyline;

[0022] Each contour line in the drawing must be composed of straight line segments, and the line segments must not be curved;

[0023] Contour lines in drawings must not cross or overlap;

[0024] All contour lines in a drawing must be on the same layer.

[0025] Preferably, the step S3 comprises:

[0026] S31: Input contour layer, east-west component dx of sun ray vector at 1m height, north-south component dy of sun ray vector at 1m height, and height h from the ground;

[0027] S32: Specify a contour map, and add all contour lines in the contour map to the selection set, i.e., the contour selection set;

[0028] S33: Specify the point to be tested and determine whether it is a two-dimensional point. If it is a two-dimensional point, call any method for solving the ground height of the two-dimensional point in the contour map and update the point to be tested to a three-dimensional point. If the height of the two-dimensional point cannot be solved based on the contour lines around the point to be tested, the two-dimensional point of the point to be tested remains unchanged, and the direct end flag is defined as "yes".

[0029] Preferably, the step S4 comprises:

[0030] S41: If the direct end flag is "yes", the remaining steps are not executed, and the maximum occlusion value is set to "?", and the three-dimensional point where the maximum occlusion value is generated is set to "none";

[0031] S42: Obtain all contour lines that may block the point to be measured, and establish a selection set of contour lines to be calculated;

[0032] S43: construct a counter and set the initial value to 0;

[0033] S44: constructing a three-dimensional intersection parameter list;

[0034] S45: obtaining one of the contour lines in the contour line selection set to be calculated, and obtaining all the two-dimensional line segments of the contour line, and sorting the elements in the two-dimensional intersection point list and updating the two-dimensional intersection point list, in order of the top-down distance between each two-dimensional point in the list and the point to be measured from small to large;

[0035] S46: combining the elevation of the contour line obtained in step S45 with the first two-dimensional point in the two-dimensional intersection list to obtain a three-dimensional intersection, and calculating the occlusion value generated by the three-dimensional intersection, and combining the occlusion value with the three-dimensional intersection and adding it to the three-dimensional intersection parameter list;

[0036] S47: The counter performs an increment operation;

[0037] S48: Repeat the steps from S45 to S47, the number of repetitions being the number of contour lines in the contour line selection set to be calculated;

[0038] S49: If the three-dimensional intersection parameter list contains at least one element, delete the duplicate elements in the three-dimensional intersection parameter list so that the elements in the list are different, sort the elements in the three-dimensional intersection parameter list and update the three-dimensional intersection parameter list, and arrange them in order from large to small according to the occlusion value stored in each element in the three-dimensional intersection parameter list, and then obtain the first element in the three-dimensional intersection parameter list, which stores the maximum occlusion value and the three-dimensional point where the maximum occlusion value is generated; if the three-dimensional intersection parameter list is an empty table, that is, the contour line selection set to be calculated is an empty set, that is, all contour lines in the contour map do not meet the three screening conditions described in S42 in the specific implementation method, that is, all contour lines in the contour map are not qualified to occlude the off-ground test point, then the maximum occlusion value is set to "∞", and the three-dimensional point where the maximum occlusion value is generated is set to "none".

[0039] Preferably, the step S5 comprises:

[0040] S51: If the maximum occlusion value is "∞", the current color is changed to yellow; if the maximum occlusion value is "?", the current color is changed to cyan;

[0041] S52: If the three-dimensional point where the maximum occlusion value is generated is not "none", a straight line is drawn to represent the occlusion line, with the starting point being the point to be measured and the end point being the three-dimensional point where the maximum occlusion value is generated.

[0042] On the other hand, a system for drawing the degree to which a certain point is blocked by a mountain based on CAD is provided, which is used to implement any of the above-mentioned methods for drawing the degree to which a certain point is blocked by a mountain based on CAD.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] 1. The present invention makes full use of the characteristics of contour maps. When the sun's ray vector is known, a three-dimensional straight line is drawn at a certain point in the topographic map, which intuitively shows the mountain shadow and records the degree of shading. This facilitates land planning for the mountain photovoltaic industry and mountain agriculture, avoids arranging photovoltaic modules and crops in areas with severe shadows, and increases power generation and agricultural output.

[0045] 2. The present invention takes into account the regulations on the distance from the ground for mountain photovoltaics and mountain agriculture. The operator can input the distance from the ground to perform shadow detection that is more adapted to industry standards.

[0046] 3. The present invention has a wide range of applications and is applicable to any parallel light projected downward other than vertical light. No modification or adjustment is required before applying this method to tropical or southern hemisphere mountains.

[0047] 4. The contour map is complex and it is difficult to tell with the naked eye which areas are blocked by mountains. Sometimes when the owner asks why photovoltaic modules or crops are not arranged in certain areas, the designer can call on the method described in this patent and answer on the spot in a short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a flow chart of the method of the present invention;

[0049] Figure 2 It is a schematic diagram of the sun's ray vector at 9:00 local time of the present invention;

[0050] Figure 3 It is a schematic diagram of the cross section of the mountain to be measured according to the present invention;

[0051] Figure 4 It is a schematic diagram of the maximum occlusion value of the present invention;

[0052] Figure 5 It is a textual schematic diagram of the occlusion line and the maximum occlusion value of the present invention. DETAILED DESCRIPTION

[0053] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0054] In the present invention, terms such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "side", "bottom", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are relational words determined only for the convenience of describing the structural relationships of the various parts or elements of the present invention, and do not specifically refer to any part or element in the present invention and should not be understood as limitations on the present invention.

[0055] In the present invention, terms such as "fixed connection", "connected", "connection", etc. should be understood in a broad sense, indicating that it can be fixedly connected, integrally connected or detachably connected; it can be directly connected or indirectly connected through an intermediate medium. Relevant scientific research or technical personnel in this field can determine the specific meanings of the above terms in the present invention according to specific circumstances, and they should not be understood as limiting the present invention.

[0056] Example:

[0057] like Figure 1 As shown, the following steps are included:

[0058] S1: Collect standardized contour drawings;

[0059] S2: For the collected contour drawings, define the input parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, height above the ground, define the concept of the test line, the test elevation, the three-dimensional intersection, the profile of the mountain to be tested, the test point above the ground, the perihelion, the aphelion, the highest height of the field, the shielding value, the maximum shielding value, the shielding line, and the text of the maximum shielding value;

[0060] S3: Input or specify the parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, and height from the ground;

[0061] S4: Calculate the maximum occlusion value and the three-dimensional point where the maximum occlusion value occurs;

[0062] S5: Draw the occlusion line and the maximum occlusion value text;

[0063] S6: Turn the sunlight from east to west and perform the steps S4 and S5 again.

[0064] The collection of standardized contour drawings follows the following principles:

[0065] All contour lines in the drawing must be of polyline type;

[0066] The height of the contour lines in the drawing should be reflected in the elevation parameters of the polyline;

[0067] Each contour line in the drawing must be composed of straight line segments, and the line segments must not be curved;

[0068] Contour lines in drawings must not cross or overlap;

[0069] All contour lines in a drawing must be on the same layer.

[0070] Parameters in step S2:

[0071] Point to be tested: The operator specifies a 3D point on the ground whose mountain shadow occlusion degree needs to be tested. If a 2D point is specified, any method for calculating the ground height of the 2D point in the contour map must be immediately called and the 2D point must be converted into a 3D point.

[0072] Contour layer: Enter a string to indicate the layer where the contour line is located, which is used to identify the contour line;

[0073] Contour map: The set of contour lines selected by the operator should at least include all contour lines that may obstruct the measured points;

[0074] The east-west component and north-south component of the sun's ray vector at 1m height: enter a real number for each component. Both numbers cannot be 0 at the same time. For example Figure 2 The schematic diagram of the sun ray vector at 9:00 local time shown, A1B1 is the sun ray vector at 1m height, A1C1 is the north-south component of the sun ray vector at 1m height, A1D1 is the east-west component of the sun ray vector at 1m height, and A1E1 is 1m height;

[0075] Height from the ground: Enter a non-negative real number to indicate the color of the drawn shading line and the maximum shading value text when the shadow shading degree of the test point to be detected is reduced by how many meters, so as to meet the height requirements from the ground specified for photovoltaic modules and crops;

[0076] Test line: The two-dimensional straight line passing through the test point from a bird's-eye view and parallel to the sun's rays from a bird's-eye view is called the test line;

[0077] Elevation to be measured: The elevation where the line to be measured is located is called the elevation to be measured;

[0078] 3D intersection point: The 3D point on the contour line that intersects with the vertical surface to be measured is called the 3D intersection point;

[0079] Profile of the mountain to be measured: The cross-section diagram formed by all three-dimensional intersections on the vertical surface to be measured is called the profile of the mountain to be measured, such as Figure 3 As shown, the profile of the mountain to be measured is parallel to the sun's rays and perpendicular to the horizontal plane;

[0080] Off-ground test point: A three-dimensional point obtained by moving the three-dimensional test point upward to the height above the ground;

[0081] Perihelion and aphelion: For any section of the sun ray, sun ray vector, line to be measured, elevation to be measured, mountain profile to be measured and their top view, the end close to the sun in the top view is called the perihelion, and the end far from the sun is called the aphelion. Figure 1 For example, A1 is the perihelion, B1 is the aphelion, Figure 2 For example, the three-dimensional intersection on the right is at the perihelion, and the three-dimensional intersection on the left is at the aphelion;

[0082] Highest height of the field: a real number, representing the elevation of the highest contour line in the entire contour map, used to specify the length of the frame line when calling the ssget function to obtain the selection set in step S42 so that the contour lines that are too far away from the test point are not taken into consideration, thereby improving the calculation efficiency;

[0083] Occlusion value: refer to the attached Figure 4, if the mountain is ignored, there is a sun ray that can illuminate the test point in the profile of the mountain to be tested. For each three-dimensional intersection point in the heliocentric direction of the test point in the profile of the mountain to be tested, there is a height difference between the sun ray and the three-dimensional intersection point. The value of the height difference is called the occlusion value. A positive height difference means that the three-dimensional intersection point cannot block the test point, and a negative height difference means that the three-dimensional intersection point can block the test point.

[0084] Maximum occlusion value: For each three-dimensional intersection point in the perihelion direction of the measured point in the profile of the measured mountain, there is a corresponding occlusion value. The maximum value of these occlusion values ​​is called the maximum occlusion value. The maximum occlusion value is the parameter finally displayed in the drawing of the present invention, which is generally a real number. However, when the height of the measured point is unknown, the maximum occlusion value is specified to be unknown and recorded as "?". When there is no contour line in the perihelion direction of the measured point that is qualified to occlude the measured point, the maximum occlusion value is specified to be ignored and recorded as "∞"; refer to the attached figure. Figure 4 It should be noted that although the elevation angle of the three-dimensional intersection point 1 to the measured point is larger, theoretically the three-dimensional intersection point 1 has a more serious occlusion on the measured point, but in order to better take the height parameter off the ground into consideration, this patent abandons the embodiment of the elevation angle parameter and only realizes the embodiment of the maximum occlusion value;

[0085] Blocking line: A three-dimensional straight line displayed on the drawing that allows the operator to observe the degree to which the off-ground test point is blocked by the mountain. The starting point is the test point, and the end point is the three-dimensional point where the maximum blocking value is generated. Cyan indicates that the off-ground test point is at least blocked by the contour line at the end point of the blocking line, and yellow indicates that the off-ground test point cannot be blocked by the contour line at the end point of the blocking line, nor by other contour lines. When the height of the test point is unknown or there is no contour line in the near-shore direction of the test point that is qualified to block the test point, the drawing of the blocking line is not executed; the blocking line is as shown in the attached figure. Figure 4 As shown;

[0086] Maximum occlusion value text: A single line of text displayed on the drawing to facilitate the operator to observe the degree of obstruction of the ground test point by the mountain. It is located near the test point from a bird's-eye view and records the maximum obstruction value. Cyan indicates that the ground test point is obstructed or the height is unknown, and yellow indicates that the ground test point is not obstructed. The maximum obstruction value text is as shown in the attached figure. Figure 5 shown.

[0087] The step S3:

[0088] S31: Input contour layer, east-west component dx of sun ray vector at 1m height, north-south component dy of sun ray vector at 1m height, and height h from the ground;

[0089] S32: Specify a contour map, and add all contour lines in the contour map to the selection set, i.e., the contour selection set;

[0090] S33: Specify the point to be tested and determine whether it is a two-dimensional point. If it is a two-dimensional point, call any method for solving the ground height of the two-dimensional point in the contour map and update the point to be tested to a three-dimensional point. If the height of the two-dimensional point cannot be solved based on the contour lines around the point to be tested, the two-dimensional point of the point to be tested remains unchanged, and the direct end flag is defined as "yes".

[0091] The step S4:

[0092] S41: If the direct end flag is "yes", the remaining steps of S4 are not executed, and the maximum occlusion value is set to "?", and the three-dimensional point where the maximum occlusion value is generated is set to "none";

[0093] S42: Obtain all the contour lines that may block the test point. The contour lines that may block the test point meet three screening conditions: one is that the elevation is greater than the elevation of the test point; the second is that it touches the perihelion part of the test line (the perihelion part bounded by the test point) from a bird's-eye view; and the third is that when the sunlight from the test point is traced back to an elevation equal to the highest altitude of the field, the sunlight has reached the top, and the test point cannot be blocked by any contour line in the perihelion direction after the sunlight reaches the top. The test point off the ground is even less likely to be blocked by any contour line in the perihelion direction after its sunlight reaches the top. The calculation based on the third condition is used to call the ssget function with the second contour line of the test point. The two-dimensional coordinates are the two-dimensional coordinates of the end point of the two-dimensional frame line segment extending from the starting point to the near side of the line to be measured. The coordinates of the point to be measured (x, y, z), the 1m height sun ray vector (dx, dy, 1), and the highest height of the field hmax are known. The coordinates of the end point of the frame line segment can be calculated as (x-(hmax-z)*dx, y-(hmax-z)*dy). Call the "ssget" function to filter all the contour lines whose elevations of the contact line segments ((x, y), (x-(hmax-z)*dx, y-(hmax-z)*dy)) are greater than z and add them to the selection set. This selection set is called the "contour line selection set to be calculated";

[0094] S43: Create a new counter "i", with an initial value of 0;

[0095] S44: Create a new empty table "3D intersection parameter list";

[0096] S45: Obtain the elevation, vertex list, and closure of the i-th contour line in the contour line selection set to be calculated, obtain all the two-dimensional line segments of the contour line through the vertex list and closure, obtain the two-dimensional intersection of the line segment ((x, y), (x-(hmax-z)*dx, y-(hmax-z)*dy)) with all the line segments of the contour line and add them to a list, called the "two-dimensional intersection list", call the CAD extension function "vl-sort" to sort the elements in the two-dimensional intersection list and update the two-dimensional intersection list, and arrange them in order from small to large according to the overhead distance between each two-dimensional point in the list and the point to be measured;

[0097] S46: Since the sun's rays shine downward, the occlusion value generated by the mountain at the first two-dimensional point in the two-dimensional intersection list must be smaller than the occlusion values ​​generated by other two-dimensional points in the two-dimensional intersection list. Therefore, the elevation of the i-th contour line in the contour line selection set to be calculated is combined with the first two-dimensional point in the two-dimensional intersection list to obtain a three-dimensional intersection (xi, yi, zi), and the occlusion value generated by this three-dimensional intersection is calculated = z + sqrt (((x-xi)^2+(y-yi)^2) / (dx^2+dy^2))-zi, and the occlusion value is combined with the three-dimensional intersection and added to the three-dimensional intersection parameter list;

[0098] S47: increment the counter i by 1;

[0099] S48: Repeat the steps from S45 to S47, the number of repetitions being the number of contour lines in the contour line selection set to be calculated;

[0100] S49: At this time, a complete three-dimensional intersection parameter list has been obtained. If the three-dimensional intersection parameter list contains at least one element, the repeated elements in the three-dimensional intersection parameter list are deleted so that the elements in the list are different. Then the CAD extension function "vl-sort" is called to sort the elements in the three-dimensional intersection parameter list and update the three-dimensional intersection parameter list. The order is arranged from large to small according to the occlusion value stored in each element in the three-dimensional intersection parameter list. Then, the first element in the three-dimensional intersection parameter list is obtained, which stores the maximum occlusion value and the three-dimensional point where the maximum occlusion value is generated; if the three-dimensional intersection parameter list is an empty table, that is, the contour line selection set to be calculated is an empty set, that is, all contour lines in the contour map do not meet the three screening conditions described in S42, that is, all contour lines in the contour map are not qualified to occlude the off-ground test point, then the maximum occlusion value is set to "∞", and the three-dimensional point where the maximum occlusion value is generated is set to "none".

[0101] The step S5:

[0102] S51: If the 3D point where the maximum occlusion value is generated is "none", then (if the maximum occlusion value is "∞", the current color is changed to yellow, if the maximum occlusion value is "?", the current color is changed to cyan), otherwise (if the maximum occlusion value plus the height above the ground is greater than or equal to 0m, the current color is changed to yellow, if the maximum occlusion value plus the height above the ground is less than 0m, the current color is changed to cyan);

[0103] S52: If the 3D point where the maximum occlusion value is generated is not “none”, a straight line is drawn to represent the occlusion line, with the starting point being the point to be measured and the end point being the 3D point where the maximum occlusion value is generated;

[0104] S53: The non-vertical sunlight is divided into 8 irradiation directions, namely, due east, due west, due south, due north, southeast, northeast, southwest, and northwest. A suitable two-dimensional offset of the insertion point of the maximum occlusion value text relative to the two-dimensional point of the measured point is specified for each of the 8 irradiation directions. The offset makes the maximum occlusion value text beautiful and clear, and the present invention does not make any provisions.

[0105] S54: Draw a single line of text with the maximum occlusion value at a suitable position near the point to be measured, with the elevation being 0. If the maximum occlusion value is a real number, the single line of text should retain 3 decimal places.

[0106] The step S6 is specifically as follows:

[0107] In the case other than 12:00 local time, the sun ray vectors that need to be considered always exist in pairs in the morning and afternoon. The influence of a group of sun ray vectors symmetrical about 12:00 local time on mountain shading is theoretically the same. Therefore, when the east-west component of the sun ray vector at a height of 1m is not equal to 0, update the east-west component of the sun ray vector at a height of 1m to its opposite number, and execute all the operations of S4 and S5 again, you can get a group of shading lines and maximum shading value text about the point to be measured, the effect is as shown in the attached figure. Figure 5 shown.

Claims

1. A method for drawing the degree to which a certain point is blocked by a mountain based on CAD, characterized in that: The following steps are involved: S1: Collect standardized contour drawings; S2: For the collected contour drawings, define the input parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, height above the ground, define the concept of the test line, the test elevation, the three-dimensional intersection, the profile of the mountain to be tested, the test point above the ground, the perihelion, the aphelion, the highest height of the field, the shielding value, the maximum shielding value, the shielding line, and the text of the maximum shielding value; S3: Input or specify the parameters of the test point, contour layer, contour map, east-west component of the sun ray vector at 1m height, north-south component of the sun ray vector at 1m height, and height from the ground; S4: Calculate the maximum occlusion value and the three-dimensional point where the maximum occlusion value occurs; S5: Draw the occlusion line and the maximum occlusion value text; S6: Turn the sunlight from east to west and perform the steps S4 and S5 again.

2. The method for drawing the degree to which a certain point is blocked by a mountain based on CAD according to claim 1, characterized in that: The collection of standardized contour drawings follows the following principles: All contour lines in the drawing must be of polyline type; The height of the contour lines in the drawing should be reflected in the elevation parameters of the polyline; Each contour line in the drawing must be composed of straight line segments, and the line segments must not be curved; Contour lines in drawings must not cross or overlap; All contour lines in a drawing must be on the same layer.

3. The method for drawing the degree to which a certain point is blocked by a mountain based on CAD according to claim 1, characterized in that: The step S3 comprises: S31: Input contour layer, east-west component dx of sun ray vector at 1m height, north-south component dy of sun ray vector at 1m height, and height h from the ground; S32: Specify a contour map, and add all contour lines in the contour map to the selection set, i.e., the contour selection set; S33: Specify the point to be tested and determine whether the point to be tested is a two-dimensional point. If it is a two-dimensional point, call any method for solving the ground height of the two-dimensional point in the contour map and update the point to be tested to a three-dimensional point. If the height of the two-dimensional point cannot be solved based on the contour lines around the point to be tested, the two-dimensional point of the point to be tested remains unchanged, and the direct end flag is defined as "yes".

4. The method for drawing the degree to which a certain point is blocked by a mountain based on CAD according to claim 3, characterized in that: The step S4 comprises: S41: If the direct end flag is "yes", the remaining steps are not executed, and the maximum occlusion value is set to "?", and the three-dimensional point where the maximum occlusion value is generated is set to "none"; S42: Obtain all contour lines that may block the point to be measured, and establish a selection set of contour lines to be calculated; S43: construct a counter and set the initial value to 0; S44: construct a three-dimensional intersection parameter list; S45: obtaining one of the contour lines in the contour line selection set to be calculated, and obtaining all the two-dimensional line segments of the contour line, and sorting the elements in the two-dimensional intersection point list and updating the two-dimensional intersection point list, in order of the top-down distance between each two-dimensional point in the list and the point to be measured from small to large; S46: combining the elevation of the contour line obtained in step S45 with the first two-dimensional point in the two-dimensional intersection list to obtain a three-dimensional intersection, and calculating the occlusion value generated by the three-dimensional intersection, and combining the occlusion value with the three-dimensional intersection and adding it to the three-dimensional intersection parameter list; S47: The counter performs an increment operation; S48: Repeat the steps from S45 to S47, the number of repetitions being the number of contour lines in the contour line selection set to be calculated; S49: If the three-dimensional intersection parameter list contains at least one element, delete the duplicate elements in the three-dimensional intersection parameter list so that the elements in the list are different, sort the elements in the three-dimensional intersection parameter list and update the three-dimensional intersection parameter list, and arrange them in order from large to small according to the occlusion value stored in each element in the three-dimensional intersection parameter list, and then obtain the first element in the three-dimensional intersection parameter list, which stores the maximum occlusion value and the three-dimensional point where the maximum occlusion value is generated; if the three-dimensional intersection parameter list is an empty table, that is, the contour line selection set to be calculated is an empty set, that is, all contour lines in the contour map do not meet the three screening conditions described in S42 in the specific implementation method, that is, all contour lines in the contour map are not qualified to occlude the off-ground test point, then the maximum occlusion value is set to "∞", and the three-dimensional point where the maximum occlusion value is generated is set to "none".

5. The method for drawing the degree to which a certain point is blocked by a mountain based on CAD according to claim 4, characterized in that: The step S5 comprises: S51: If the maximum occlusion value is "∞", the current color is changed to yellow; if the maximum occlusion value is "?", the current color is changed to cyan; S52: If the three-dimensional point where the maximum occlusion value is generated is not "none", a straight line is drawn to represent the occlusion line, with the starting point being the point to be measured and the end point being the three-dimensional point where the maximum occlusion value is generated.

6. A system for drawing the degree to which a certain point is blocked by a mountain based on CAD, characterized in that: A method for implementing the CAD-based drawing of the degree to which a certain point is obscured by a mountain as described in any one of claims 1 to 5 above.

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