LED Binary Timestamp Encoding for Precise Image Georeferencing
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Solution Overview
Problem
Existing systems for image timestamping fail to efficiently address the challenges of high-speed georeferencing, particularly at speeds exceeding 130 km/h, where temporal precision on the order of milliseconds or less is required for accurate georeferencing, and existing methods introduce errors due to imprecise acquisition time determination and rolling shutter processing.
Innovation Solution
A system comprising a timestamp generating circuit, an internal clock, individually addressable LEDs, and a processing system for encoding timestamp into images, utilizing Pulse Width Modulation (PWM) signals to encode timestamps with millisecond precision, synchronized with GNSS and Network Time Protocol (NTP) for precise georeferencing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If consumer cameras use user-set times for timestamping, then the device is simple to operate, but the temporal precision deteriorates to rounded seconds causing georeferencing errors of several hundred meters
Solution Approach 1:
The system uses the camera's internal clock to automatically generate timestamps with millisecond precision, eliminating the need for manual time setting by the user. The timestamp is embedded directly into the image metadata, making the system self-sufficient for precise time recording without requiring user intervention or external time sources.
2Device complexity
If cameras use rolling shutter processing, then the device complexity is reduced, but the temporal precision of capture moment determination deteriorates due to sequential processing of sensor data
Solution Approach 1:
The system generates the timestamp based on the internal clock before the image capture and processing sequence begins. This preliminary timestamp is then associated with the entire image data set, allowing the rolling shutter to process data sequentially without affecting the accuracy of the capture time reference, which is established in advance for the whole image.
3Loss of information
If displays are used to encode capture time, then the time is visibly recorded in the image, but the refresh rate limitation of 30 ms to 4 ms prevents millisecond precision and the display method becomes cumbersome
Solution Approach 1:
The system replaces the mechanical display refresh mechanism with an electronic timestamp embedding system. Instead of using a physical display that updates at fixed refresh rates, the internal clock generates digital timestamp data that is directly embedded into the image metadata, achieving millisecond precision without being constrained by display hardware limitations.
4Measurement precision
If GNSS technology is used for trajectory calculation, then the temporal precision is excellent with atomic clock synchronization, but at speeds of 130 km/h one centimetre is covered in just 0.28 milliseconds requiring precision beyond standard camera capabilities
Solution Approach 1:
The system merges the GNSS atomic clock time synchronization with the camera's internal clock to create a unified timestamping system. The GNSS provides accurate time reference that is combined with the internal clock's continuous timing capability, achieving the required sub-millisecond precision for high-speed georeferencing by integrating both time sources rather than relying on either alone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves millisecond-level precision in timestamping, enabling accurate georeferencing even at high speeds by encoding timestamps directly into images, reducing errors and enhancing the accuracy of existing georeferencing systems, particularly at speeds exceeding 130 km/h, enhancing the accuracy of existing georeferencing systems, particularly at speeds exceeding 130 km/h, enhancing the accuracy of existing georeferencing systems, enhancing the accuracy of existing georeferencing systems, enhancing the effectiveness of the accuracy of existing georeferencing systems, enhancing the effectiveness of the accuracy of existing georeferencing systems.
Implementation Method 1
at least one LED arranged in at least one array of the LED or LEDs... control the LEDs in the at least one array to visually code in accordance with the binary form
Implementation Method 2
utilizing Pulse Width Modulation (PWM) signals to encode timestamps with millisecond precision
Data Source
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AI summary
A system for generating time encodings. The system comprises a timestamp generating circuit configured to periodically generate a timestamp; an internal clock system operationally connected to the timestamp generating circuit, whereby the timestamp generating circuit is further configured to periodically generate the timestamp based on the internal clock; at least one LED arranged in at least one array of the LED or LEDs, obtaining respectively for each array a LED clock. The timestamp generating circuit is further configured to convert the timestamp into a binary form, and control the LEDs in the at least one array to visually code in accordance with the binary form, whereby each one of the LEDs represents a bit in the binary form. The system further comprises at least one camera, each of the at least one camera having a corresponding field of view, whereby the at least one LED clocks are placed within a respective corresponding field of view of the at least one camera. The system further comprises a processing system configured to record image data from images output from the at least one camera, comprising for each image at least a representation of the LED clock visually coding the binary form physically, encoded with the image for retrieval of information.