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Clint Merrell

Out of Memory Tips?

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Does any one have any tips on how I can increase the memory available to WMS.

I'm working with large elevation dataset and while doing things such as building tins, reading in text files (high resolution aerial survey xyz files), delineating floods, etc. I am routinely getting an "Out of Memory" error that forces me to stop what I'm doing, close WMS and open it back up. Usually I can not even save my progress because I get the out of memory error when I try to save as well.

My desktop configuration is as follows:

Core 2 Duo 2.66GHz E6750 CPU

3.00 GB RAM

32-bit Windows XP Professional SP2

I'm not multitasking while using WMS, and it seems like it can read 2 or 3 (50 MB) elevation data sets before it runs out of memory. Is there a cache I can increase or periodically empty? increase the windows page file size? Any, suggestions would be much appreciated.

-Clint

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Hi Clint,

If you already have 3 GB of RAM, increasing your windows page file size is not going to help much. I'd find ways to remove or thin out data you don't need. What kind of elevation data are you reading? Are they DEMs or TINs? DEMs actually use much less memory than TINs for each elevation point. WMS has some good tools for thinning out data you don't need for both DEMs and TINs. You can clip polygon areas from DEMs, only read in the sections of DEMs in your study area, and thin your DEMs when reading them into WMS. If you have several TINs, you can read each TIN individually, filter out unwanted data in each TIN, and merge the TINs together when you are done filtering them. Hopefully this information gives you some things you can try out. Most of the time if you run out of memory with your elevation data, the processing time required to process your data with today's processors will just be too long (days or months) and you need to thin your data to do any real work. Tech support should be able to help you if you are having trouble with thinning down or clipping out your unneeded elevation data.

Thanks for the post,

Chris

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Thanks Chris,

The Data is from an Aerial survey. It is in the form of a comma delimited text file (X,Y,Z) and the elevations are taken on a grid at 5 foot intervals. I've been importing the text file as "survey data" which is basically the same as "tin vertices," if I'm not mistaken. Then I've clipped it down, but the area covered is around 300 acres of the LA River floodplain in downtown Los Angeles, and there is just too must data. I'd like to figure out some way to thin out the points in the flood plain, but retain the points near the river because it is the best resolution I'm going to get for the channel area.

This may just be a moot point in this case because the aerial survey did not make any correction to try to remove the buildings, so there are tons of abnormal peaks in the surface. I will probably just abandon this data set and get another one.

Thanks for your help though,

Clint

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Hi Clint,

After getting some data that works for you, the filter command in the TIN menu is probably what you need. This command lets you filter the points on your TIN to a certain angle. We usually recommend using 4 or 8 degrees for the angle. You can also trim only the vertices you want on your TIN using the "Trim" command in the TIN menu. There is also a merge command that helps you to merge TINs together. Also remember that you can always convert between DEMs and TINs so you can merge DEM and TIN data together.

Chris

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