Global Mapper exporting empty elevation tiles from a downloadable source? Help!

360NoScope

Hello!

I currently use Global Mapper v17.0 64-Bit on a Windows 7 system.  I have more RAM than sanity and enough hard drive space to sink a ship.  Here’s my issue; I’ve gotten access to the Korean VWorld server data source for elevation data (the one that is listed in the File > Download Online Imagery/Topo/Terrain Maps... window), and I am able to load my desired location into Global Mapper to analyze, but I’m running into problems exporting.  Firstly, the data source only seems to want to download when I use increments of 50km, I’ve been able to download 50, 100, 200, and 500km data sets and save them as GMWs, but anything smaller than 50 Global Mapper just crashes.  That’s weird, but not my main issue.  To start, I load a data set like this one here:

(SEE attached photo "Figure 1b - A Lovely Data Set.png")

 

Then I go to export Elevation Grid Format (GeoTIFF), and choose the following settings.  These are bounds whose dimensions are specific to the project I’m working on, and have worked successfully countless times with other data sets both offline and online (the CONUS NED10m data set works every time).  For vertical units I've used both meters and centimeters without cause for concern, in this example Meters are used.  Here’s what the export settings look like:

 

(SEE attached photo "Figure ii - Export Settings Galore.png")

 

In this example I am only exporting 1 randomly placed tile of 2016m x 2016m dimensions to test since I haven’t gotten this data set to work yet.  In the future I would like to export a much larger area.  Now then, when the export finishes and I import that tile into a fresh global mapper session this is what I get:

 

(SEE attached photo "Figure 3 - 14 Sad Face Emoticon.png")

 

Just a blank screen.  The distance ruler is there, but the elevation ruler is gone.  Global mapper has recognized the UTM zone and the coordinates will properly scale as you move the mouse around the screen, but there is no elevation data.  This is quite disheartening.  I am able to export imagery (as in, Export Raster Image Format of the Atlas Shader that the elevation data creates [seen above]) with no issue.  For some reason, the elevation data is getting lost when I export.  As a side note, I am able to create area features based on the elevation of this data set in global mapper (e.g. flattening an area, smoothing terrain, etc.) I can think of a few different reasons why this would be the case:

1) My network is too slow to actually export the data.  I’m connected through a convoluted corporate network structure which can and has caused slowdowns, and I wouldn’t be surprised if they had blocked some port that allowed me to download data from the Korean server in the first place.  Network slowness is also my suspect cause for why I can only download data sets in increments of 50km, maybe I have just gotten lucky when I tried those areas.  Is there a way I can check to see if this is the case?

 

2) This data set / data vendor has some exception in place on the API Key that does not allow users to export once it has been downloaded.  This would make me very sad as this is the most promising looking source of international elevation data I have seen so far.  I don’t think this is the case as I can export an image of the elevation (the Atlas Shader mentioned above) without issue, but is there a way I can check to see if this is the case?  Please note that I do not speak or read Korean, I received that API Key through sheer force of will and a few lucky clicks on their website.

 

3) Global Mapper is having trouble exporting from a downloaded source.  This is related to network slowness, but when I load up the data set from the Korean VWorld server, or export, or zoom in (or any other function really), I am confronted by huge slowness while it re-draws the area.  I imagine this is because almost every function is requiring Global Mapper to re-download or re-parse the elevation data.  100% of the time when I load a Korean VWorld data set Global Mapper will go into “(Not Responding)” mode, but if I just wait it out it will usually finish loading.  It also goes into “(Not Responding)” mode very briefly at the beginning of any export I do with this data set.  That little hiccup could be where all the elevation data is getting lost.  (When I export from other downloaded sources like the NED CONUS 10m source, I do not get these “Not Responding” hiccups).

 

I realize I’m shooting in the dark here and when it comes down to it I don’t have much of a clue in terms of networking and the overall architecture of Global Mapper, but if there is anything I can do to make these exports work that would just be so dandy.  Also, is there a way to save this data set locally other than exporting and re-importing?  Saving as a GMW does not seem to do the trick, it apparently still has to download that data even if it is cached somewhere.  I imagine saving it locally would alleviate all of these problems.  I’ve looked through a gratuitous amount of documentation on the subject and can only find information about saving Imagery data locally (again a process which is just exporting raster image format and re-importing), but if there were a way to save this data set offline, or just getting an export to work, I would be the happiest little lamb there ever was.  Please let me know!

Help me Globi-wan KenobalMapper, you’re my only hope.

bmg_bob

Hello,

Thank you for the detailed description.  I recommend getting the latest release of Global Mapper to see if the problem has already been fixed.  If the problem persists in the latest version, then we can move ahead.  

You mentioned that Global Mapper crashes when you download a data set smaller than 50 km.  Please send the information from that error message.  Also, please provide a screen capture of the original download request so we can attempt to reproduce the problem.  It would probably be useful to send a screen capture of a successful download also.

Cheers,

Bob

360NoScope

Bob!

Thanks for the reply.  I am currently downloading the latest version of Global Mapper to see if it fixes the export issue.  On the western front, you can see the attached screenshots on what a successful (Figure 4) and failed (Figure 5) download look like:

Figure 4 - Successful Dataset Download



Figure 5 - Failed Dataset Download



The only thing not pictured in the above images is the little pop-up that requires the API Key.  For some reason my false sense of security didn't think it would be a good idea to put that in a screenshot online, but alas it lists my API Key in the error message above, so that was a fruitless undertaking.  

It took Global Mapper about 25 minutes to produce that error message, it just sat there in "(Not Responding)" mode once I clicked "OK" to download the data set.  I have seen a different error message pop-up, one that was directly mentioned "C++", but I don't have a screenshot of that and not enough time left in the day to reproduce it.  The error message above is much more common though (~98% repro).  Also note that the session it creates after the error message exhibits similar behaviors to the empty tiles I am getting as the result of exporting from these data sets, it recognizes the lat/long positions, is scaled properly as if it had imported a tile, etc., but contains no elevation data.  The only difference between the successful data set pictured here and the one in my original post is that I had changed the projection from Geographic to UTM, as that's what I usually use to export.

I will be out of the office for the rest of the night, but I'll be back in tomorrow morning to check on any updates and provide further information if you have any questions.

Thanks!

360NoScope

Good morning!  A little update-

I have downloaded and installed the latest version of Global Mapper, and all of the above issues still exist.  I'll attach a screenshot (Figure VI - The Full Monty) detailing the my entire export / import process.  Please note that in the screenshot, when the export progress bar goes into the "(Not Responding)" state, it will stay like that briefly, then begin loading from 1-100%.  The result of this is the empty black tile, which when loaded into Global Mapper produces the blank session all the way on the right.

I used an analysis tool called gdal to analyze the tile (as well as others I have exported), and it displays the two dimensional bounds of the tile as well as the datum and other information, but when told to analyze the min/max elevation values it displays that those values do not exist.



Please let me know if I can provide more information or further testing, thanks!

bmg_bob

Hello,

Have you tried exporting the full area that you have downloaded?  When you are working with online data for the same area on a regular basis, it is usually best to export that data to a Global Mapper Grid (or other elevation grid/raster format of your choice, depending on the type of online data), and use the local data set in your workspace instead of the online data.

With regard to your workflow:  

Based on the error message in Figure 5 above, it looks like the server is not returning any data when Global Mapper sends a request for a relatively small amount.  I believe that this is what is happening during your export as well, even though no error message is being displayed.  When you export data from an online data source, Global Mapper has to download the tiles during the export process.  Since you are exporting a small portion of the total area, Global Mapper would be sending a request for that area, and it appears that request is failing.

You might be able to confirm this by turning on logging in Global Mapper as follows. 

1. Use the Tools->Configure... menu item or the Configuration button to open the configuration dialog.  
2. On the General tab, scroll to the bottom of the list under Miscellaneous Advanced Options.  
3. Make sure the "Enable detailed logging" option is checked, and click OK.
4. Close Global Mapper
5. Browse to your Global Mapper User Data Folder and delete the file called errlog.txt, if it exists.  (You can find the user data folder location on the About Global Mapper dialog displayed when you choose the Help->About Global Mapper...)
6. Start Global Mapper and run your workflow.
7. Global mapper will create a file called errlog.txt in the Global Mapper User Data Folder.
8. Post the errlog.txt file on this thread.

Do you have another way to get data from this server so that you can test whether or not it has the capability of returning small amounts of data?  To a large extent, Global Mapper is at the mercy of the online server and the network when making these requests.

Cheers,

Bob

360NoScope

Bob!

Thanks for the insight.  As of now I have not tried to get the data directly from the source, there's a language barrier there to tackle but I might try that sometime next week.  I've attached the error log that was created as a result of my current workflow, from downloading the data to the completed export of 1 empty elevation tile.  I will also attempt a larger export of a grid to use offline, though if the elevation data is the 2 meter resolution as advertised this will take a long time so I'll let it run over the weekend and check the results on Monday (I'm out of the office tomorrow).  Again, I appreciate the help with this process!

360NoScope

Another little update:

I started a .GMG export of one of the downloaded data sets, where each tile was going to be 20km x 20km using centimeters for the vertical units.  When I came in this morning, the first tile export was only at 47% completed.  Under my Resource Monitor > Network Activity tab, globalmapper.exe was showing send / receive values of less than 50 bytes / sec.  Seems prettttttyyyyyyy slow...

Those tiles would be rather large, but when I did a few test exports of much smaller .gmg grid files, those exports completed but the tiles were empty, similar to the original issue.  In exporting 20km x 20km tiles I attempted to grab a larger portion per export so the network wouldn't lose interest in me, so to speak.  I hope that makes sense!  Please let me know if there is anything else I can try.