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JKM

Importing GIS Contours?

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Thanks Chris, I did get this into a TIN but can only use linear contours because of the size. I have 32 GB of RAM and a Quadro 4000 video card and it is still killing my machine. What would you suggest I do with this data set to make more manageable? I have a SMS license as well and I'm looking at the available tools there. Thanks, John

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John,

Depending on what you need the elevation data for, I'd recommend converting your TIN to a DEM after reading it. You can do everything on DEMs that you can do on TINs in WMS, and the DEM should use less memory. Be sure to set the cell size of your DEM to your desired elevation point spacing. It could take a long time to convert. You have plenty of RAM, but you could still run up against the limit when trying to display as many triangles as you have on your TIN.

There are other options as well. I think there was a previous thread on this forum where somebody discussed using contour data and I gave them some suggestions. If you want to use your elevation data inside of SMS, you should be able to save it as a TIN file from WMS and then read the TIN into SMS. Let me know if you have any other questions.

Chris

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This forum is for the WMS software. If you need to read your data into SMS, I recommend posting your question on the SMS forum. I think some of the same tools to import data are available in SMS that are available in WMS.

Thanks,

Chris

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In order to delineate our watershed we are using DEM (Digital Elevation Model). But when I import two adjacent DEM files, WMS reads them but they do not appear adjacent in the import dialog. We tried to modify the projection characteristics but it doesn’t work .How could we fix the problem? Thank you!

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Fadoua,

Here is something you can try if your DEMs are not coming in together in the Import DEMs dialog:

1. Set your desired projection using Edit | Current Projection in WMS 9.1 (Display | Display Projection in WMS 10.0 beta)

2. Right-click on the Terrain Data folder in the project explorer and select "Open Digital Elevation File(s)..."

3. Select the DEM files you want to import.

4. After the DEM files are imported, if they're in the right location and adjacent to each other, multi-select the files you want to merge into a single DEM (use the Shift or Ctrl key to multi-select) and select the "Merge DEMs" menu item. Enter a cell size for the merged DEM (you can probably just use the default value) and select OK.

Let me know if you have any troubles or further questions.

Thanks,

Chris

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Chris,

Thank you for your valuable explications.

Unfortunately it doesn’t work. In fact, our watershed covers five MTM projection zones. So whenever we change the projection parameters to set those of the new zone, the previous imported DEMs files disappear. Also, when we tried to merge imported DEMs, a gap appeared between layers that should be adjacent and whose projection zones are different.

MTM is Modified Mercator Transverse associated to projection system of Eastern Canada.

Thanks,

Fadoua

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Fadoua,

It could be that one of your DEMs is in a different projection than the other DEM. If you put your DEMs on our FTP site, I can have a look at them and see if I can get them in the same projection or figure out what the problem is. If you follow the steps I describe above, the DEMs should actually show up next to each other even if they're in different projections. Are your sure your DEMs are adjacent to each other?

If you decide to send the DEMs, you can put them at ftp://pubftp.aquaveo.com/incoming

It's an anonymous FTP site, so anybody can upload files there and I can get them. Send me a message when you've uploaded your files.

You can also contact the tech support team (http://www.aquaveo.com/technical-support) and they can help you with the problems you're having.

Thanks,

Chris

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Chris,

I have just uploaded the DEMs file at FTP site. The file name is: Simulation_test_Fadoua. You will find a view of the problem that we had. I would like to note that the DEMs represent northern Quebec in Canada.

Thanks,

Fadoua

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Fadoua,

I was able to read your DEMs into WMS, but I think there are some gaps in your DEM data. I think your DEM tiles should have an East (ending in "e") and a West (ending in "w") DEM associated with them. The DEMs you sent only have the East DEMs, but I was able to read them into WMS using your MTM coordinate system. Here are the steps I followed to read your DEMs:

1. Select File | Add Data | Add GIS Data...

2. Add all your DEMs.

3. Set your projection to MTM using Edit | Current Projection in WMS 9.1 (Display | Display Projection in WMS 10.0 beta). Make sure your horizontal and vertical units are the same (both either need to be meters or feet).

4. Right-click on each of your GIS raster files (DEMs) and convert each one to a WMS-style DEM under the Terrain Data folder. You have to convert each one individually. It's time-consuming, but this is the best way to do it.

5. After you've converted all your DEMs to WMS-style DEMs, you can select all your DEMs under the terrain data folder, right-click on them, and merge them. Use the default cell size as I describe above and select OK.

The option I describe to import all your DEMs into the terrain data folder at once does not work because WMS creates a separate grid when importing each DEM. When you merge the DEMs, the DEMs do not quite line up correctly. So follow the steps above and you should be able to get a seamless DEM for your entire area. Be sure to include both the East and West tiles as I describe above.

Let me know how it goes. Thanks,

Chris

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Chris,

Finally it works. We reviewed our DEM files and followed your explications to fix the problem.

I would like to thank you for your quick and relevant response.

Thanks,

Fadoua

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