Remote sensing image tile dynamic aggregation method for high pixel density display

Abstract

This invention relates to the field of remote sensing satellite data application technology. To address the problem of blurry display of 256×256 pixel satellite image tiles on high-resolution displays, a dynamic aggregation method for remote sensing image tiles designed for high pixel density displays is proposed. First, a maximum of n-level tiles of all 256×256 pixels are pre-generated. Then, different aggregation methods are adopted based on the request mode and the tile level in the tile address to obtain all tiles at the corresponding location. After aggregation, the tiles are returned to the client and rendered at the original 256×256 pixel tile locations, thereby significantly improving the visual clarity and detail of non-highest level tiles on high-resolution displays.

Description

Technical Field

[0001] The present invention relates to the technical field of remote sensing satellite data applications. Background Art

[0002] Common satellite image tile services usually provide standard tiles of 256×256 pixels. Due to the pyramid model of the tiles and the quadtree segmentation characteristics, for tiles in the Web Mercator projection coordinate system, one tile at level z corresponds to 4 tiles at level z+1 (the resolution is 2 times that of level z) and 16 tiles at level z+2 (the resolution is 4 times that of level z).

[0003] Under the background of the increasing popularity of high-resolution displays, such tiles are prone to problems such as blurred display and unclear details. The fundamental problem lies in the mismatch between the physical pixels of the screen and the logical pixels of the image. On a high-resolution screen, one logical pixel may correspond to 2 or even 4 physical pixels. At this time, if a 256×256 pixel tile is directly stretched and displayed, each logical pixel needs to be filled by multiple physical pixels through an interpolation algorithm, resulting in phenomena such as decreased image sharpness, edge jaggedness, and detail loss. Summary of the Invention

[0004] In order to solve the problem of blurred display of common 256×256 pixel satellite image tiles on high-resolution displays, the present invention provides a dynamic aggregation method for remote sensing image tiles for high pixel density display. The specific technical solutions are as follows: Pre-generate all tiles of 256×256 pixels at the maximum level n; According to different request modes and the tile levels in the tile address, different aggregation methods are adopted to obtain all tiles at the corresponding positions; After aggregation, return to the client and render it at the position of the original 256×256 pixel tile, so as to obtain higher display clarity.

[0005] Furthermore, for the tiles at levels 1 to n that have been pre-generated, add the parameters "@2x" or "@4x" to the tile address accessed by the client, which respectively represent obtaining tiles in 2x or 4x mode. After being parsed by the server, the corresponding aggregation method is called.

[0006] For tiles in 2x mode, when z < n levels, provide 512×512 pixel tiles aggregated from 4 tiles at level z+1 at the corresponding position; For tiles in 4x mode, when z < n-1 levels, provide 1024×1024 pixel tiles aggregated from 16 tiles at level z+2 at the corresponding position; when z = n-1 level, provide 512×512 pixel tiles aggregated from 4 tiles at level z+1 at the corresponding position; If z=n level or does not contain the "@2x" or "@4x" parameters, provide a pre-generated 256×256 pixel tile for that level.

[0007] Technical effects: The proposed method for dynamic aggregation of remote sensing image tiles for high pixel density display can meet the high-quality display requirements of satellite image tiles. On the server side, based on parameters input from the client, high-level tiles are dynamically aggregated and rendered to their original 256×256 pixel tile locations, such as... Figures 2 to 4 As shown, this ensures that non-top-tier tiles can display clearer and sharper image details on HD screens or screens of the same resolution, thereby significantly improving the visual clarity and detail performance of non-top-tier tiles on high-resolution displays.

[0008] This invention achieves a high-efficiency balance between quality, storage, and computation. Existing clients primarily render satellite imagery using two methods: pre-generated tiles and real-time resampling. For high-resolution screens, pre-generating all high-resolution tiles (e.g., 512×512 pixel tiles) incurs significant storage costs, while real-time resampling places extremely high demands on computational resources and response time. This invention, based on pre-stored 256×256 pixel tiles, dynamically aggregates high-level tiles on demand, avoiding the storage pressure of pre-stored high-resolution tiles and mitigating the high computational costs of real-time processing of raw large datasets. It achieves a good engineering balance between image quality, storage overhead, and service performance. Attached Figure Description

[0009] Figure 1 This is an overall flowchart of an embodiment of the present invention.

[0010] Figure 2 This is a diagram showing the standard tile layout and its corresponding magnified display effect.

[0011] Figure 3 This is a diagram showing the 2x mode tiles and their corresponding magnified display effect.

[0012] Figure 4 This is a diagram showing the 4x mode tiles and their corresponding magnified display effect. Detailed Implementation

[0013] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort using the embodiments of the present invention are within the scope of protection of the present invention.

[0014] This embodiment provides a method for dynamic aggregation of remote sensing image tiles for high pixel density displays, such as... Figure 1 As shown in the figure, it specifically includes the following steps: First, pre-generate full-scale 256×256 pixel tiles up to level n on the server side; the client uses any software or program that supports the TMS / WMTS tile service protocol to request tiles.

[0015] For the tiles that have been pre-generated at levels 1 to n, determine whether the tile address accessed by the client contains the parameter "@2x" or "@4x", which respectively represent obtaining tiles in 2x or 4x mode, and call the corresponding aggregation method after parsing on the server side.

[0016] If it contains the parameter "@2x", it is in 2x mode, that is, the resolution is doubled. For tiles in 2x mode, if the tile level z < n, provide a 512×512 pixel tile aggregated from 4 tiles of level z + 1 at the corresponding position; If it contains the parameter "@4x", it is in 4x mode, that is, the resolution is quadrupled. For tiles in 4x mode, if the tile level z < n - 1, provide a 1024×1024 pixel tile aggregated from 16 tiles of level z + 2 at the corresponding position; if z = n - 1, provide a 512×512 pixel tile aggregated from 4 tiles of level z + 1 at the corresponding position; If it does not contain the parameters "@2x" or "@4x", it is in the normal mode, and provide the pre-generated 256×256 pixel tiles of this level. If the tile level z = n, there are no higher-level tiles, and also provide the pre-generated 256×256 pixel tiles of this level.

[0017] It is known that the origin of the tile coordinates of the TMS service protocol is at the lower left corner, and the origin of the tile coordinates of the WMTS service protocol is at the upper left corner, and the y-axis direction is opposite. Therefore, for tiles of the TMS service protocol, the encoding of the corresponding higher-level tiles and the position relationship of the tiles encoded as z / x / y are shown in Tables 1 and 2: Table 1: Encoding and position relationship of the corresponding z + 1 level tiles

[0018] Table 2: Encoding and position relationship of the corresponding z + 2 level tiles

[0019] For the tile encoding of the WMTS service protocol, the encoding of the corresponding higher-level tiles and the position relationship of the tiles encoded as z / x / y are shown in Tables 3 and 4: Table 3: Encoding and position relationship of the corresponding z + 1 level tiles

[0020] Table 4: Encoding and position relationship of the corresponding z + 2 level tiles

[0021] Furthermore, based on the input encoding and parameters, after obtaining all the high-level 256×256 pixel tiles required for the corresponding encoding position in this mode, image processing operations are performed using the Sharp library, an open-source library based on the Apache-2.0 license: combining the 2x or 4x mode and the size relationship between z and n of the current tile level, the Sharp library is used to create a 512×512 pixel or 1024×1024 pixel 3-channel (webp, jpg format) or 4-channel (png format) blank image; the composite method of the Sharp library is executed to aggregate all the 256×256 pixel tiles to be aggregated into the blank image according to the corresponding position relationship in the table above, and generate buffer data of the corresponding format.

[0022] Furthermore, determine whether the current tile needs to be watermarked. If so, calculate the watermark generation position and watermark text size based on the size of the aggregated tile, and ensure that the watermark display effect is consistent with that of the 256×256 pixel tile. Similarly, use the composite method of the Sharp library to overlay the watermark image onto the tile and return the Buffer data.

[0023] All content not described in detail in this specification belongs to the prior art known to those skilled in the art. Furthermore, for those skilled in the art, there will be changes in specific implementation methods and application scope based on the ideas of this invention. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. A method for dynamic aggregation of remote sensing image tiles for high pixel density display, characterized in that, The steps are as follows: Pre-generate full-scale 256×256 pixel tiles up to level n; According to the request mode and the different tile levels in the tile address, different aggregation methods are adopted to obtain all tiles at the corresponding positions; After aggregation, return to the client and render it to the position of the original 256×256 pixel tile, so as to obtain higher display clarity.

2. The method for dynamic aggregation of remote sensing image tiles for high pixel density display according to claim 1, characterized in that, For the tiles at levels 1 to n that have been pre-generated, add the parameter "@2x" or "@4x" to the tile address accessed by the client, which respectively represent obtaining tiles in 2x or 4x mode. After parsing on the server side, call the corresponding aggregation method.

3. The method for dynamic aggregation of remote sensing image tiles for high pixel density display according to claim 2, characterized in that, For tiles in 2x mode, if z < n levels, provide 512×512 pixel tiles aggregated from 4 tiles at level z + 1 at the corresponding position; For tiles in 4x mode, if z < n - 1 levels, provide 1024×1024 pixel tiles aggregated from 16 tiles at level z + 2 at the corresponding position; if z = n - 1 levels, provide 512×512 pixel tiles aggregated from 4 tiles at level z + 1 at the corresponding position; If z = n levels or there is no "@2x" or "@4x" parameter, provide the pre-generated 256×256 pixel tiles at this level.

4. The method for dynamic aggregation of remote sensing image tiles for high pixel density display according to claim 1, characterized in that, According to the incoming encoding and parameters, obtain all high-level 256×256 pixel tiles required at the corresponding encoding position in this mode; perform image processing operations: create a blank image with 3 channels or 4 channels of 512×512 pixels or 1024×1024 pixels, aggregate all 256×256 pixel tiles to be aggregated into the blank image according to the corresponding position relationship, and generate Buffer data in the corresponding format.

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