TransDEM - Southern Hemisphere?

[Steven G.]

Hello,
Question for Roland. In attempting to georeference a bitmap, I have followed the suggestion of inputting a Lat/Long instead of having to convert to UTM. It doesn't seem to accept a negative (or South) value for Latitude. eg 38:26:32S or -38.4421 etc entered into the 'Nord' field is accepted as a Latitude but seems to default to a northern hemisphere value. (Entering UTM converted coordinates works fine.) I am doing something wrong here?

Regards,
Steven.

[Roland Ziegler]

Hello Steven,

I may have been too quick with my suggestion entering lat/longs directly.

I have noticed a couple of glitches when working with southern hemisphere data, three or four issues on my list. But that one is new to me. I'll have a look at it early next week and if it it is a bug hope to fix it quickly.

[Steven G.]

Thanks Roland. I have been thinking about the problem that I was having. (The georeferenced bitmap was reversed horizontally.) Possibly it was actually not the Latitude but the Longitude value or the way it was entered that was the problem? The value of Longitude that I wanted to enter is roughly 145 degrees East, is TransDEM expecting a positive or negative value for this?

Regards,
Steven

[Roland Ziegler]

Steven,
both lat and long values should allow for minus signs. I had a very brief look into the source code this morning and found a sign variable there. So basically I did consider negative values.

I'm sure you entered the coordinates in the correct order: first value in pair = easting = long, second = northing = lat

Longitudes should be -180° to +180°, latitudes -90° to +90°, at least, that was the idea.

Which format did you try for the coordinates?

I will test with an online map source on Monday. Yesterday I found the NSW map portal on the web: http://maps.nsw.gov.au/viewer.htm Their maps carry lat/long coordinates.

After this test I should be able to say more about this.

[Steven G.]

Thanks Roland. I'll play around a bit more to see if I can get it to work. Interesting link you gave for the NSW maps. Gave me the idea to find if similar info available for Victoria, which is the area I am working on at the moment...
http://services.land.vic.gov.au/landcha ... ractivemap


Thanks,
Steven.

[Steven G.]

Also looks like the UTM coordinates are available directly off the online victorian map site as well. Which is good for georeferencing with TransDEM.

Steven.