TransDEM Forum

The Resources thread about USGS GeoPDF (viewtopic.php?f=2&t=236&start=0) gives very clear instructions for importing these into TransDeM and converting them into georeferenced maps for further use. This is great!

Geophil's post of 02 May 2013 in that thread indicates automated cropping of these maps is possible after import using the transparent margins tool.

Unfortunately, when I activate the Transparent Margins tool by clicking on the icon (or choosing it from the "Raster Map" drop down menu), all options, including the scissors to "Crop margins applying rectangular mask" as well as functions under Raster Map like "Convert to UTM" are grayed out and unavailable.

I cannot figure out from the 02 May posting how to continue the cropping.

Well, I just conducted an experiment.
It seems the right thing to do is import the map, then immediately convert to UTM before clicking on the Transparent Margins tool. It is just as predicted; the cropping takes place. Wonderful. There is no need to click on the Transparent Margins tool at all!

I will post this anyway despite needing no help because it might be useful to someone else. If the moderator thinks it surplus I have no objection to its deletion.

Hi, WindsorSpring.

Your method doesn't seem to work for me. I've been mainly using historical topo maps from The National Map Viewer and when I load a goePDF and immediately click "Convert to UTM", TransDEM does so, but leaves the map margin intact.

Instead, what I've been doing is loading the geoPDF, clicking "Transparent Margins" once, which puts a "yellow" line around the map at the margin line. I then click "Transparent Margins" again, which shades the entire margin in "yellow". My last click is to "Convert to UTM", which crops the margin and then gives me just the converted map (sans margin), ready to save!

Andrew

You are correct, Sharknose.
Initial conversion to UTM converts the margins, too leaving a white mess!
The sequence that works and that worked for me in the first post (but I forgot the two steps) was the same as you describe:
o Open the GeoPDF in TransDEM (margins are white)
o Click on the Transparent Margins tool (this marks the neat line in yellow, but grays out other functions)
o Click the Transparent Margins tool again (the margins darken from pure white)
o Convert to UTM
This crops the map and orients it.

When writing the chronicle of the experiment at the end of the previous post, I forgot that I had clicked the Transparent Margins tool twice.

I cannot blame my forgetfulness on seeing NS 8104 "Lehigh Valley" pull a train behind my house during lunch because I made the posting before lunch! It was an unusual and welcome sight on the BNSF Cuba Sub, though.

Excellent catch! I too live within sight of a railroad (CSX Trenton Line) and I've been seeing many BNSF (plus NS, CN & CP occasionally) locos pulling crude oil trains on their way from North Dakota to Philadelphia!

Oh, and it seems we're in sync with our TransDEM margin cropping!

Andrew