Our unique process
PhotoSat has invented a new satellite elevation mapping process based on oil and gas seismic processing technology. Our geophysical process generates elevation grids with over four times the accuracy of conventional photogrammetric maps derived from the same stereo satellite photos.
Conventional photogrammetric survey
Key components of our geophysical processing system:
1. Adaptation of seismic processing systems: The geophysicists at PhotoSat apply signal enhancement, noise attenuation, and image matching from seismic data processing to automatically produce high accuracy elevation grids from stereo satellite photos.
2. High resolution stereo satellite photos: New high resolution and high accuracy stereo satellites assist in achieving 30cm or better elevation accuracies. Using seismic processing tools we calculate and plot the correlation between the stereo satellite photos as vertical profiles:
3D surface of maximum correlation
3. Graphics Processing Units (GPUs): PhotoSat’s algorithms lend themselves to using multi-core GPUs that enable the hundreds of millions of 2D Fourier transforms needed to automatically produce topographic grids. This has resulted in a 20x improvement in throughput, allowing us to deliver projects in short timelines.
4. Extensive experience: We have completed over 1000 mapping projects, and work with the satellite companies to continuously improve our ability to attenuate the systematic errors in the satellite data and improve the elevation accuracy.
5. Robust image and topographic geometry: Our technology involves a single bulk shift and fine adjustments to the pitch, role, and yaw of the stereo satellite photo pairs. There is no point to point or polynomial warping of the satellite photos or elevation grids. By maintaining the integrity of the satellite topography we can verify the relative accuracy of most ground survey points to within 30cm vertically and 50cm horizontally.
PhotoSat is the only company in the world that has demonstrated the capacity to produce satellite surveys with better than 30cm elevation accuracy, as measured by thousands of accurate ground survey points and by direct comparison to highly accurate LiDAR surveys. We also provide an accuracy assessment with every project.