3D satellite photo showing some of the 775 ground survey points

PhotoSat publishes 21 new satellite surveying accuracy studies

3D satellite photo showing some of the 775 ground survey points

3D WorldView-2 satellite photo of Asmara, Eritrea, showing some of the 775 ground survey points that determine the 14cm PhotoSat surveying accuracy.

21 PhotoSat surveying accuracy studies from seven different stereo satellites

PhotoSat has published 21 new satellite surveying and mapping accuracy studies, now available on our website. The studies include data from seven different stereo satellite systems. The best results show elevation surveying accuracies of better than 15cm.

The accuracy studies include stereo satellite data from the following satellites:

  • WorldView-1
  • WorldView-2
  • WorldView-3
  • Pleiades-1B
  • KOMPSAT-3A
  • SPOT-7
  • ALOS PRISM

 

PhotoSat has measured accuracy on over 750 stereo satellite surveying projects

PhotoSat has delivered over 750 satellite surveying projects since 2007 and we have carried out accuracy evaluations on the majority of them. Most of the survey data on these projects belongs to our customers and cannot be shared publically; however, customers have provided feedback on many of these projects.

The results of these 21 new accuracy studies are consistent with our project accuracy evaluations and customer feedback.

 

PhotoSat accuracy test areas in Eritrea and California

The accuracy studies were conducted over two test areas. One test area is west of Asmara, Eritrea where PhotoSat has access to more than 45,000 ground survey points over a 50km by 20km block.

The second area is in SE California where PhotoSat uses a very accurate Opentopography.org open source LiDAR survey.

 

The effect of different numbers of ground survey points

The studies employed different numbers of ground survey control points for each test area and each satellite system. For some of the satellite stereo pairs the accuracy is significantly improved by increasing the number of ground survey control points.

For example, the WorldView-2 survey for Eritrea is accurate to 19cm in elevation with two ground control survey points, and accurate to 14cm in elevation with 21 ground control points.

In contrast, the accuracy of the WorldView-3 survey for the California test area is not improved by additional ground survey points. This WorldView-3 survey is accurate to 13cm in elevation with one ground survey control point and with 153 ground survey control points.

 

PhotoSat has been continuously producing satellite accuracy studies since 2007

In order to provide objective quantifiable accuracy data for stereo satellite surveying and mapping, PhotoSat has been continuously producing accuracy studies since 2007. We have previously published nine of these studies. The rest of the studies were used for calibrating and improving our processes.

 

21 new accuracy studies all processed with the same version of the PhotoSat processing system

The 21 new accuracy studies were produced with the most recent version (2016) of the PhotoSat processing system. Where possible we used satellite data produced by the 2015 or 2016 versions of the satellite operators’ ground processing systems.

 

Summary of PhotoSat 2016 accuracy study results

Satellite Test area km² GCP RMSE
WorldView-3 California 150 1 13cm
WorldView-3 California 146 153 13cm
WorldView-3 Eritrea 100 21 15cm
WorldView-2 California 173 1 15cm
WorldView-2 California 173 153 12cm
WorldView-2 Eritrea 100 21 14cm
WorldView-1 California 174 153 14cm
WorldView-3 Eritrea 198 2 19cm
WorldView-2 Eritrea 400 2 19cm
WorldView-1 Eritrea 100 21 19cm
WorldView-1 California 174 1 23cm
WorldView-1 Eritrea 420 9 23cm
Kompsat-3A California 144 14 21cm
Pleiades-1B Eritrea 189 74 26cm
Pleiades-1B Eritrea 189 1 28cm
Kompsat-3A California 144 1 50cm
Kompsat-3A Eritrea 130 11 48cm
Kompsat-3A Eritrea 130 1 53cm
SPOT 7 Eritrea 1,458 1 4m
ALOS PRISM Eritrea 2,300 3 2m
ALOS PRISM Eritrea 2,300 1 4m

See PhotoSat’s accuracy studies overview for full details.

For more information about PhotSat’s surveying accuracy, please see our satellite surveying case histories or visit the following links.

Satellite surveying

PhotoSat 3d elevation image

Comparison to LiDAR verifies accuracy of WorldView-3 satellite elevation mapping to within 15cm

Back in March this year, we were proud to announce that we’d verified the accuracy of DigitalGlobe’s WorldView-3 (WV3) satellite topography. The digital terrain model PhotoSat produced from DigitalGlobe’s WorldView-3 stereo satellite data was found to be accurate to within 15cm in elevation. Of course, that meant our customers could look forward to unprecedented accuracy from us, with an accuracy study to back it up. Here’s the original piece from PRNewswire:

 3d elevation image

PhotoSat 3d elevation image from WorldView-3 satellite data of the Garlock Fault in California

Engineers to benefit from high quality elevation products

VANCOUVER, March 25, 2015 /PRNewswire/ – PhotoSat is pleased to announce that the elevation data processed from DigitalGlobe’s new 30 centimeter resolution satellite, WorldView-3, has been verified as accurate to within 15 centimeters. DigitalGlobe is a leading global provider of commercial high-resolution earth imagery products and services, and is the first company to offer 30 cm resolution satellite imagery commercially.

For the study, PhotoSat produced a 50 cm grid of elevations using its proprietary geophysical processing technology with stereo satellite images taken by WorldView-3. The resulting elevations were then compared to a 50 cm LiDAR elevation grid in Southeast California, accurate to approximately 5 cm in elevation and available on the OpenTopography website. The size of the comparison area was 88 square kilometers. The resulting 15 cm RMSE elevation accuracy was impressively achieved using a single ground reference point. The full WorldView-3 accuracy study is available on the PhotoSat website at www.photosat.ca/pdf/garlock-30cm-wv3-elevation-accuracy-report-mar2015.pdf.

PhotoSat’s highly accurate elevation grids have been used for years by oil and gas and mining engineers as a cost-effective alternative to ground surveying and airborne LiDAR mapping. The satellite imagery from WorldView-3 will allow PhotoSat to deliver the highest quality topographic data yet.

“The DigitalGlobe WorldView-3 satellite data is the highest quality satellite photo data that PhotoSat has ever processed,” said Gerry Mitchell, President of PhotoSat. “In this test, an elevation grid extracted from stereo WorldView-3 satellite photos matches a highly accurate LiDAR elevation grid to better than 15 cm in elevation. This result takes satellite elevation mapping into the engineering design and construction markets and directly competes with LiDAR and high resolution air photo mapping for applications like flood plain monitoring.”

“The fact that PhotoSat has validated our elevation data to within 15 cm is amazing and even exceeds our initial expectations,” saidKenyon Waugh, DigitalGlobe’s senior director of vertical segment products. “With these elevation products, customers in the oil, gas, and mining sectors can leverage our truly global reach and realize cost savings on the order of 50 percent.”

LiDAR and satellite elevation data

LiDAR grid compared to PhotoSat’s WV3 grid. Comparison of the LiDAR and WV3 elevation grids for a 1000m wide area. Minor differences between the elevation grids are visible.

 

About PhotoSat

PhotoSat has invented a new technology that generates the world’s most accurate satellite topographic mapping.  This engineering quality data shortens timelines and eliminates surveying delays in all phases of resource and engineering projects. We have delivered over 500 highly accurate elevation mapping projects, and have published a number of accuracy studies which are available on our website. For more information please visit www.photosat.ca.

About DigitalGlobe

DigitalGlobe is a leading provider of commercial high-resolution earth observation and advanced geospatial solutions that help decision makers better understand our changing planet in order to save lives, resources and time. Sourced from the world’s leading constellation, our imagery solutions deliver unmatched coverage and capacity to meet our customers’ most demanding mission requirements. For more information, visit www.digitalglobe.com.

To find out more, either visit us at  www.photosat.ca, view the original accuracy report here or contact us at info@photosat.ca.