TransDEM Forum

First of all; I wish to thank Geophil and Gisa for all the precious infos dispensed. In fact, it's in Gisa's fourth video that I discovered that you can automate georeferencing of Google Earth's map tiles. Up to now I was was doing it the semi-automatic way as written in the Transdem infos; VERY long and tedious.

For some reason, when making up map tiles with Google I almost always get the infamous follow-up error. I say almost because it happens once in a while that I'm able to get the maps I manually vectorized... I assume I must be doing something wrong or right.... Long story short, here's a video capture of my actions below this paragraph. Quick explanation: using DEM file 31H06, (St-Jean-sur-Richelieu, Quebec, Canada) I traced a simple polyline/vector and used it as a guideline for maptiling with Google...

http://www.bicot.ca/videos/followuperror2.avi


Computer infos:
Core2quad Q9300
4 Gb memory
WD black HD 500Gb
WD Green HD 1Tb
vid card: 9800GT
Win 7 64bit

Thanks for your answers.

edited once for clarity.

I always assumed that was a communication error with google or other map provider. I get them pretty often and what I do is, I tell the server to get maps along route and save them to a clean subdirectory, then start the download along the route, if I get the error I then split the polyline just inside the last map and remove the part of the route that has completed, then just start again from that point saving to the same directory and transdem will adjust the name to tileMap-002_001_georef.png or similar and it will keep going. There are large routes with hundreds of maps that have error-ed on me 5 or 6 times and I just keep doing the same thing and they all get downloaded.

Then when I go to reload them if you select *.lgb when opening geo referenced raster maps you will see tileMap-001.lgb tileMap-002.lgb tileMap-003.lgb etc. which are I guess are header files that tell transdem what files are in that particular group. Just load them instead of the individual files and it will load all the maps in that sequence.

Hope I explained that right and there may be an easier way but that's how I handle it and it works for me everytime...

Ok I watched your video and have seen that as well. Have you tried microsoft's server or yahoo? Also I am not sure if it helps or not but what I do is I do everything you do up to the point of selecting orhtophotos and I select map, then zoom in to the area where I want up to 17 zoom Then select ortho and I will see the photo in the big screen. Being that you are not getting anything in the big screen in that dialog box tells me there is a connection issue because the screen remains black. If you try google and map it should come up with a map of the world in there and if you zomm in to about 9 or higher then switch to othro it should see the ortho in that screen and it should download...

Scsi, even if the preview screen was black, I was indeed plugged on the server. The screen was black because if you start out in orthophoto mode, the image display is black; if I change over to map mode, it is indeed displayed, and once I click back to ortho, the map image is displayed also. In one of Gisa's video it was mentionned also.

I don't think the display affects how the software does its work; it's there to give you an idea of the quality of the image and tells you if indeed you are plugged on the server, which is was for sure... That's why I did not bother to ajust it in the video capture.

Thanks for your swift answers btw.

No problem, that's the extent of my expertise though maybe Roland or others can elaborate further.

On a side note google orthos for me at this time doesn't come up. Microsoft and yahoo are fine and respond quick but google is lagging. I am on a DSL in Yuma Az and a crappy one at that

Oh yeah! Never bothered using yahoo, assuming (falsly) that my region wouldn't have enough definition (like MS virtual earth): turns out that I can zoom up to 17 before the map becomes unavailable. I usually run @ 18.

So there you go, it's indeed Google that's giving me trouble! Using Yahoo, I was able to cover both railways in St-Jean and Iberville in one shot.

I prefer Google for it's better resolution, so I'll wait a day or two before I decide if I'm using Yahoo for my tiles, hoping things could get back to normal on Google's part.

As far as I know, the provider may limit the number of ortho photo clippings for non session mode, plain web server access, the way TransDEM works. Rumours say that's to prevent the flight sim folks from painting their terrain on-the-fly. If you are connected to the internet by dynamic IP address you could try to reset your connection to get a new address.

Here's a good one: finally nailed it using Google Earth software version 6.0.1 to view the map tiles. The source of the problem stems from a change of date the Google's pictures where taken: here a link where trouble happens: http://www.bicot.ca/autres/0163.kmz

On the right, the pictures where taken in 2002; no problem whatsoever for many kilometers, on the left, pictures taken in 2010... Each time I tried to make tiles with these, the follow-up error would pop up....

Any idea why it happens?

To bypass the problem, for that part of my tiles, I used yahoo instead with good but less precise results...

http://www.bicot.ca/images/stjeantransdem.jpg

PS never underestimate how much memory you need... Often, during my testings of big regions, my memory use was over 5 Gb! (including OS & all). All went fine.

Yeah if you are grabbing 200 tiles memory can go bye-bye fast...