08-18-2017 06:54 AM - last edited 2 weeks ago by ian.anderson
Where can I ask for some information about ERDAS Imagine? Regarding perspective-to-plane transformation and orthocorrection what are the conditions to receive high accuracy and does the software generates automated reports about transformation?
I actually need to provide answers to these questions and I kindly ask for help and directions to find it faster
Solved! Go to Solution.
08-21-2017 09:25 AM
These questions have been answered for you in a support ticket. We sent you a message with the ticket ID number. The answers are provided below, but we would like to continue any further discussion in your ticket via the Support Portal.
Q1. Does ERDAS IMAGINE do perspective-to-plane transformation by following the procedure for creating precise geometrically attached raster images (Raster > Transform & Orthocorrect > Control Points > Projective Transform)?
Q2. Regarding transformation of perspective images is it appropriate to use reference image gained from unmanned aircraft that is photogrammetrically processed?
A2. Yes, if the UAV image is already orthorectified.
Q3. Would deviations in the reference image lead to deviations in the transformed image?
A3. Yes, any deviation in the reference image will lead to a deviation in the transformed image.
Q4. What input data/information is needed in order to do such transformation?
A4. Ground Control Points (GCPs) will need to be collected. The Projective Transform models are simulation models purely solved by the GCPs. However if you are using any elevation data then make sure that the elevation information has the correct vertical elevation values and datum. Otherwise elevation data can also introduce errors in the transformed image.
Q5. Is there a complete match between reference and transformed image after processing and if not - what are the dependencies?
Q5. It will be very close depending on the polynomial order used and the number and accuracy of the GCPs.
Q6. Does ERDAS IMAGINE calculate deviations while preparing transformed image?
A6. Yes, the RMS Error is calculated when adding and editing GCPs.
Q7. Is it possible and under what conditions the transformed image to provide +/- 1 cm accuracy for spatial geometric inquiries?
A7. Even with high resolution imagery it is very difficult to get +/- 1 cm accuracy. The Projective Transform Model is based on Rational Polynomial Functions. The higher the polynomial order the more flexibility there is and better results. But a higher order polynomial requires more GCPs and they must be distributed evenly across the image.
Q8. Does ERDAS IMAINE prepare automated report after completing the procedure and what transformation information does it contain?
A8. The RMS Error is generated after your model is solved.
Hexagon Geospatial Support