10-23-2017 05:50 PM
Text from Julie's post:
I want to ask if you have an idea on how to fuse a 2D image and an elevation image into a single image with merged information from the two combined images? I am thinking of using layer stacking but I don't know if the information will also merge.
10-24-2017 12:25 AM
I have done this and commented to Julie privately already too. In nutshell my trial has been simple layer stack and adding elevation layer as a one band. Then feeding this mixed data image to Objective and extracting buildings etc. My trials were not a total triumph to success but as an idea this is a way to feed image data and elevation data easily to single feature exctraction process. It is just question how smart the data can be processed in feature extraction and I did not find the optimal ways yet.
10-24-2017 02:18 AM - last edited on 10-24-2017 05:13 AM by ian.anderson
I've done this as well, however using a relative height layer (DSM - DTM) and found it's worked a little better in Objective. It's a shame that the workflow isn't a little more customisable and that you can't use defined height layers in the raster processing steps. Roll on ERDAS IMAGINE 2018 with a lot of the Objective type operators in Spatial Modeler!
10-24-2017 03:31 AM
10-24-2017 05:24 AM - edited 10-24-2017 05:28 AM
If you are going to layer-stack the terrain layer with your multispectral imagery as an input to IMAGINE Objective I would strongly recommend scaling the data to approximately similar ranges first. Otherwise the "aberrant" band can have an undue effect on the Objective process.
So if your MS data is 11-bit (0 - 2047), scale the DEM to that range. Or vice versa.
Johnnie is correct - if you are trying to classify "off ground" items like trees, buildings, etc., having the DEM as Height Above Ground is much more likely to produce good results than Height Above Mean Sea Level. But if you are classifying vegetation types, which may depend on altitude, then ASL may give better results.
...and don't forget that there's now an Ideas board if you want to make enhancement requests!
10-24-2017 05:34 AM