TransDEM Forum

I am working on a route map from Willard Ohio to Just west of Hicksville Ohio on the CSX line. I have the Dem done and am now trying to get a Topo raster on top of it. I am using the Web mapping Services and the USGS Raster Graphics (topo maps) from the USA MS REsearch Maps (TerraServer). I started at Willard and headed west. Getting coordinates from Google maps and entering them and getting maps. I got to Hamler Ohio where it changes from Zone 17 to Zone 16 and that is where my problems started. No matter what coordinate I put in for the East number Transdem would change it and give me a map way east of where I wanted and would change the east number from -84.024 to -78.042. If I entered a number higher like -84.765 it would be a bit higher in the -78's to. I cannot seem to get any maps in zone 16 to appear where they should west of zone 17. I have looked at the transdem pdf's but couldn't find anything that was helpful. If anyone has any idea how I can get the zone 16 maps to appear and stop transdem from changing my number (I tried clicking the "fix" button but that didn't help.) I would very much appreciate it.

Mike

G'day sturmtiger,

Hmmm. Methinks something isn't quite right here. When this has occurred to me in th past, TransDEM has 'asked' me if I would like it to "transpose" the 'errant' maps (which it does to trick itself into thinking they are in the same zone), so that it can then treat them as 'one whole' (but you don't seem to be getting this request)...

...mind you, I may have that completely wrong, so it might be wise to wait until "the good doctor" picks up this post and provides ,ore details or the correct response...

Jerker {:)}

No I am getting no option to change anything. I just starts the process of getting the map and then as it pops it on the screen it changes the coords. and places it way to the east.

There are a couple of aspects with a route spanning more than one UTM zone to be kept in mind.

First of all, TransDEM fully supports route building across UTM zone boundaries. Most of the handling is automatic, too.

Mathematically, any TransDEM route must lie in a single UTM zone. We will call it the primary zone. To accomplish this, this primary zone can be made wider than originally defined by the UTM coordinate system. Any geo data from an adjacent zone must be converted to the coordinates of the primary zone.

The primary zone should be the one with the most track.

The easiest way to convert between zones is to use the DEM and the TransDEM function "Convert UTM zone". The DEM loaded determines the zone.

A DEM composed from from smaller DEM clippings, using the TransDEM "Add DEM" function will always be merged into the UTM zone of the first DEM.

Hint: If DEM resolution is high, zone conversion will take significant time. To speed up for the purpose of zone switching, re-sample the DEM to a much lower resolution like 250m ("New DEM Raster Width") and use this DEM for all UTM zone activities.


Now for the map clippings:

MS Research Maps require coordinates in the native zone range. If the WMS returns the Great White Void or yields an error message, switch to the adjacent zone via the "Convert UTM zone" function (DEM must be loaded). Then access the WMS again. This way you will get georeferenced map clippings from both the primary and secondary zone, but don't worry.

Once a DEM has been loaded in TransDEM, existing georeferenced map clippings or vector data from adjacent UTM zones will be converted automatically when opened on top of the current DEM.

MS Research Map clippings will show white margins beyond UTM zone boundaries. These can be edited manually in TransDEM using the relatively new "Transparent Margins" function. Note that there will usually be a small residual map error where the zones meet.

I hope this helps.