05-16-2017 06:06 AM
OrthoResample tool - DTM source
Is it possible to use a height model given in ERDAS HFA file format
within this tool?
Up to ERDAS 2014, the tool was called "OrthoRadar" and usage of ERDAS HFA
files as DEM input was no problem. As of version 2015 the tool is called "OrthoResample"
and I get the same bad results for Orthorectification of SAR images wether I use
constant height 0 or the height image that worked well before ERDAS 2015.
And the geolocation results are not very precise.
ERDAS IMAGINE 16.00.0000 Build 650
05-17-2017 02:57 AM
Hiya. I've had issues with the Orthoresample tool as well and have logged a support case. I've found using a simple spatial model (attached) works on the whole. However, I've also had issues using some height models with that as well. It seems that WGS84 LL DEMs don't work consistently, but if you use a metric system (UTM for instance) then that works fine. I'd be interested if anyone else was experiencing these issues.
05-17-2017 06:40 AM - edited 05-17-2017 07:02 AM
I'm using the OrthoResample tool within the Radar Toolbox for orthorectification
of synthetic aperture radar images. I tested raster DEMs (ERDAS HFA format) with
WGS84/LatLon and also WGS84/UTM horizontal projection. The vertical reference was
always WGS84. Both failed and the result was the same as using constant height 0 m.
To me it seems that the height image is totally ignored during the orthorectification
process of the radar images. Unfortunately there is no useful output in the ERDAS
For other users of the Radar Toolbox: The old "OrthoRadar" tool still exists in ERDAS 2016.
Open a command window (File|Session|Launch Command Window) and if the installation
of ERDAS IMAGINE is in the default path, just paste the following in the command line. Then
press ENTER and after a few seconds the start dialog appears.
"C:/Program Files/Hexagon/ERDAS IMAGINE 2016/bin/Win32Release/warptool.exe" "-m" "SAR (Synthetic Aperture Radar)"
05-19-2017 06:39 AM
I have been looking at this and there does seem to be an issue. One way to circumvent the issue and to maybe help in productivity is simply set the elevation source using the Metadata editor. (See snapshot). Once set the image will orthrectify on the fly in the viewer.
Be careful with the elevation file, it should have the same vertical spheroid and datum as the SAR file.
The old "OrthoRadar" can be accessed a little more easily via the radar analyst -> tools tab -> Otho Radar Classic.