DEM Data and Google Earth

[dricketts]

Thanks for the Google Earth info. I'll wait to tackle that after I get this microdem merge figured out.

Well I've done 3 merges now in microdem with varied results but none are really correct. My first I tried merging 5 different DEM files (not sure if this is what you refer to as quads). The Tiger data matched up perfectly everywhere but some large sections had no elevation change in surveyor (something around 56.3 if I remember correctly). The lowest point on the entire map should be about 67. Some other sections the elevations looked perfect.

The last 2 merges I added a 6th DEM file. I got a new error message with each attempt when the HOG utility tried to generate the .gnd file:

"Error: tile template file tile_blank.dat not found or failed to open."

I'm not sure what that is referring to.

I think I'll try another merge now still using the same downloaded DEM files. My gut feeling is something is not working right with the merge and microdem. I've been following the directions included in the help file with microdem under "DEM Merge."

Wish me luck and if you have any thoughts they would be greatly appreciated.

............................................

Well I'm already back. I noticed some odd lines in the Data Manipulation window with my latest attempt. So I thought I would post them. There should be 9 DEM files total and I've renamed them.

Blue Springs.DEM.SDTS.TAR.GZ meters z range: 217 to 306 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
Edwardsville.DEM.SDTS.TAR.GZ meters z range: 223 to 325 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
Grandview.DEM.SDTS.TAR.GZ meters z range: 224 to 330 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
Independence.DEM.SDTS.TAR.GZ meters z range: 213 to 323 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
Kansas City Mo.DEM.SDTS.TAR.GZ meters z range: 219 to 309 m UTM zone=15 NAR-C Level 2 Horizontal spacing: 30
Incorrect datum; not included in merge
Lees Summit.DEM.SDTS.TAR.GZ meters z range: 230 to 330 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
N KC Mo.DEM.SDTS.TAR.GZ meters z range: 216 to 321 m UTM zone=15 NAR-C Level 2 Horizontal spacing: 30
Incorrect datum; not included in merge
Pleasant Hill.DEM.SDTS.TAR.GZ meters z range: 253 to 321 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30
Strasburg.DEM.SDTS.TAR.GZ meters z range: 247 to 319 m UTM zone=15 NAS-C Level 2 Horizontal spacing: 30

Merge: 7 with: 2159 cols, 1423 rows
All DEMs read
Merge save, C:\mapdata\DEMs\KC2.DEM

 

[geophil]

Not sure about those codes for geodetic datums. Most quads will be NAD83 but you may find a few which are still NAD27.

You can save a lot of merging by downloading custom-made DEMs from USGS Seamless Server. Go for NED DEMs there.

 

[Dermmy]

"Error: tile template file tile_blank.dat not found or failed to open."
I'm not sure what that is referring to.

HOG will allow you to browse to locate the DEM and Tiger images, but in fact they must be put into the HOG program folder.

Andy

 

[dricketts]

geophil,

Thanks for the reply. I'm no expert on geodetic datums but in layman's terms it sounds like the reference points are not matching up with my downloaded DEMs. I thought about trying a different set of DEMs so your suggestion makes sense to me.

Will the microdem program still work with the NED DEMs from seamless.usgs.gov? Should I use the 1 arc second data set?

 

[geophil]

Will the microdem program still work with the NED DEMs from seamless.usgs.gov? Should I use the 1 arc second data set?

MicroDEM should be able to read the Seamless Server downloads. It is quite a versatile DEM viewer. I recommend to download in GeoTiff format, for optimal vertical resolution if you decide to use TransDEM later. And 1 arc sec is a good value to start. With 1/3 arc sec data volume becomes less manageable.

 

[dricketts]

I'm not sure which file to point microdem to. The download contatined a zip file containing these files and folders. I can't get microdem to read or open any of them.

These are my selections for the download on Seamless Server. I didn't see any selection or info about GeoTiff format.

 

[Dermmy]

I am not absolutely certain, but let's assume that seamless data is handled by Microdem in the same way as quad data, in which case don't unzip the download, point MicroDem at the zipped folder as downloaded...

Andy

 

[geophil]

I didn't see any selection or info about GeoTiff format.

These instructions may help: http://forums.auran.com/trainz/showpost.php?p=168178&postcount=141

 

[dricketts]

I just got the merge to work with mircoDEM before I checked the forum again.

The key on the Seamless Server site is to click on "Modify Data Request" and change the format from ArcGrid to GeoTIFF. Unzip the package then point MicroDEM to the newly created tiff file. Looks similar to TransDEM.

I really like the way Seamless Server site works. Just click and drag your selected area. I selected a large rather large area and microdem opened with no problem.

Now I'm still having that same pesky error with the Hog utility:
"Error: tile template file tile_blank.dat not found or failed to open."

I've already successfully created smaller maps with HOG and varified the targa files are in HOG folder. Maybe I should reinstall HOG?

 

[dricketts]

I have the entire map created in Trainz now. The elevations and Tiger data look good and well merged but Trainz grid is gone.

It looks as if there has been a light pink texture applied evenly over the entire map surface. Any ideas what happened here?

 

[Jerker]

G'day dricketts,

The problem with regard to your error...

"Error: tile template file tile_blank.dat not found or failed to open."...

...is very simple to fix. Dermmy pointed you in the right direction to do so but clearly, you didn't read his solution well enough to understand. Although HOG will allow you to browse anywhere in your system to find the files you need, the *.gnd file being created MUST, at all times, be located in the SAME folder where the native tile_blank.dat file is located. When I used the HOG creation method (many moons ago before before I, too, became one of the converted and started using TransDEM exclusively), I would save myself lots of work by creating the *.gnd file in the HOG root folder (where tile_blank.dat is located) and then move it to the Trainz map folder and replace/overwrite the existing *.gnd file created by Trainz with it. This worked every time, without error...

...the only other solution to avoid the error, would be to copy the tile_blank.dat file into every folder in Trainz where you are creating the *.gnd file. You see, a whole lot more unnecessary work...

Now, as for the pinkness of the 'map'. Can you provide a little more information please (a screenshot would be nice, too) as I am not exactly sure where the problem is here (other than what it is)..

Jerker {}

 

[dricketts]

Here you go.

The first few test maps I did turned out perfect except for the merging.

Today I finally merged several DEMs and TIGER data sets perfectly together to make one large Trainz map. But now I'm getting this odd looking result. No grid and the pinkish looking texture over the entire map. Again the elevations & TIGER data look perfect. For a moment I thought the DEM & Tiger data now coming from two different sites might be the culpret but its not. I tested that therory and still get the same results as below.

 

[geophil]

HOG textures are purely monochrome, the don't carry the grid. Usually these textures are only placed for the TIGER line features. This gives the grid a chance to survive. In your case they seem to have been placed everywhere. Which HOG texture set are you using? The one for TIGER or the one for aerial imagery?

 

[dricketts]

Sorry. I'm not sure what you're asking.
Which HOG texture set are you using? The one for TIGER or the one for aerial imagery?

Are you suggesting I might have downloaded incorrect Tiger data or HOG is not configured properly?

 

[geophil]

It's been a long time ago so my comments may not be as precise as they should be. I think there are 72 HOG textures altogether. 8 of those were designed for use with TIGER data and have bright colours. The remaining 64 were for use with certain aerial imagery with as tendency to pinkish and brownish hues. Somewhere in the HOG setup procedure you have to decide which part of the texture set you want to use.

For each Trainz ground vertex HOG picks one texture, taking the corresponding colour pixel value from the given bitmap as the key. In the TIGER case HOG is also supposed to leave all areas blank where there are no TIGER line features. The mapping of colour to texture is an arbitrary one. The rules for this are stored in a file which is part of the HOG distribution.

 

[Dermmy]

Remove the folder for HOG19 from your Trainz installation, load the map and select 'Delete Missing Content'. That will rid you of the pinkish texture and reveal the grid...

Andy

 

[dricketts]

Thanks Andy! That got rid of the pink texture and brought back the Trainz grid.

After closer review of the map it seems the major roads tiger lines are missing and the tiger lines themselves are not quite the right color. An odd shade of red and railroad and water lines are the same color. Not that the color of the Tiger lines is a huge deal but I thought it might help diagnose the problem.

I can recreate the map again (practice makes perfect), but how can I assure not to recreate the same problem and the HOG19 folder?

 

[Dermmy]

I have the same two problems with the last half dozen or so HOG maps I have created:

1: HOG19 overlay is always there on new maps: The solution is to not re-install HOG19. You will always get a 'Missing Content' message when you load a new HOG route, but you know exactly what is missing and hit 'Delete missing content' on the first load.

2: On recent maps the Tiger lines for railroads and waterways are the same dark blue on the route. This can be downright confusing on some maps. If there is a fix it eludes me still. Oddly the mini-map still shows the rail in 'Teal'.

I have no idea what has brought these two change about, possibly a change in the newer Tiger data itself???

Tiger often has minor roads missing, but major roads are usually there. If there are not too many roads missing it should be possible to eyeball them in from Google images...

Andy

 

[geophil]

I checked my old HOG installation. There is a "textures.txt" file. This is the colour-to-texture mapping rule which will be applied. To set-up HOG properly for TIGER data, the default, which is for aerial images, should be replaced by "hog_tiger.txt", in the subdirectory "presets". Texture #19 is part of the aerial imagery set.

 

[dricketts]

I have no idea what has brought these two change about, possibly a change in the newer Tiger data itself???

Andy

What gets me is I created my first 3 or 4 small Trainz maps with the same Tiger Data and they came out perfect. I went back and tried to create a small Trainz map with my original DEM and Tiger downloads and got the odd Tiger line colors and pink surface.

Andy can you post a screen shot of your folder structure for HOG? I somewhat stumbled my way through the install & wewain's tutorial for this. He always referred to a single "HOG" folder. I have 5. I'm not sure if this is significant but I thought I would check. I've always worked with the hog100 folder.