USGS NEDs and MicroDEM causing strange ridges in my maps

[ThatDonGuy]

I am currently using MicroDEM and HOG to convert USGS NEDs (from the "Seamless Server") into GND files. While most of the elevations look correct, I get some strange "ridges" and "troughs" that appear in straight lines, with the ridges (which tend to appear only on flat land) having notches in them at regular intervals.

It appears as if the problem is with some sort of grid on the .TGA file being generated by MicroDEM, but I don't see anything on the map that would cause it. (Then again, as the ridge/trough is rather small in height, it wouldn't take that much of a color change to make it.) Has anybody else had this sort of problem?

 

[clam1952]

I am currently using MicroDEM and HOG to convert USGS NEDs (from the "Seamless Server") into GND files. While most of the elevations look correct, I get some strange "ridges" and "troughs" that appear in straight lines, with the ridges (which tend to appear only on flat land) having notches in them at regular intervals.

It appears as if the problem is with some sort of grid on the .TGA file being generated by MicroDEM, but I don't see anything on the map that would cause it. (Then again, as the ridge/trough is rather small in height, it wouldn't take that much of a color change to make it.) Has anybody else had this sort of problem?

2009 SP1 by any chance?
If it's the same problem I was getting the grid corresponds to the board edges and prior to SP1 the ridges were very pronounced! There was a workround to get rid of the problem........ it's on the forum or maybe elsewhere, the problem was common to microdem and transdem and involved merging the dem to a blank board, sorry I have forgotten exactly the procedure as it was back around Christmas last year when I was creating the gnd file for the current route I'm working on. It did however leave small versions of the same much as you are describing. where it was obvious I got rid of them by careful use of the plateau tool elsewhere after texturing they were not visible. I got my data from a different source by the way so oubt that has any bearing.
I have a feeling the problem shouldn't exist in SP2?