In 2009 PhotoSat invented a new stereo satellite elevation surveying process that was originally based on oil and gas seismic processing technology. Our geophysical process generates elevation grids that have several times the elevation accuracy of maps derived from the same stereo satellite photos using conventional photogrammetric processing.

PhotoSat survey

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. Since 2018 we have improved our process by adding Deep Learning image matching and image feature extraction routines.

2. High resolution stereo satellite photos

New high resolution and high accuracy stereo satellites assist in achieving 20cm or better elevation accuracies. Using seismic processing and Deep Learning 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 and Deep Learning processes needed to automatically produce topographic survey 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 1,000 surveying projects. We work with the satellite companies to continuously improve our ability to attenuate the systematic errors in the satellite photos and improve the elevation surveying accuracy..

5. Robust image and topographic geometry

Our technology involves fine adjustments to the pitch, role, yaw and skew of the stereo satellite photo pairs. We use no point to point or polynomial warping of the satellite photos or elevation grids. By maintaining the integrity of the satellite photo geometry, we can verify the relative accuracy of ground survey points to within 10cm vertically and 25cm horizontally.

The result

PhotoSat is the only company in the world that has demonstrated the capacity to produce satellite surveys with better than 20cm 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.

Accuracy Report: Comparison to LiDAR

PhotoSat compared the elevation accuracy of its topography to a LiDAR dataset. The result was an accuracy of 15cm RMSE.

View the Accuracy Report.

For more information, contact PhotoSat at or 1-604-681-9770