I can see something things. What is the scale of your work? Do you have a data line or individual point? You don't need a large DEM for terrain correction. You need one DEM about 20 Km around each station. You don't need more. Then why not make DEM for a litle number station gravity that make the work process more efficiently and less time?Actually i have the terrain correction for the last work. I have tha data in the higway and only make the DEM for 25 km around it. I don't need more.
Cheers Date: Tue, 29 Dec 2015 16:00:45 +0000 From: [email protected] To: [email protected] Subject: Re: [geonet] Terrain Grid Problem Hi,not sure what has happened to take 3 days to create a large terrain grid in your example. Perhaps the grid cell sizes of your two input DEM and output terrain correction grids was set very fine, or the terrain correction (TC) optimization was not set to faster? Did you mask and minimize your regional input DEM to be a window less than <=400 km on a side? The gravity module has been used here to create TC grids using regional 90 m cells from SRTM data that go out to ~ 150 -200 km from a station and local DEM 25 m cells that go out to 1000 m and these took several minutes but quite a bit less than one hour using the Geosoft gravity module (on a 4 year old quad processor laptop). The TC optimization setting was set to "faster" in this example. The final TC grid was a few mb in size, not into the hundreds of mb. What grid cell sizes were used for your local and regional DEM grids that created the TC grid?When creating the TC grid I'd first double check the input grid cell sizes on both your local correction DEM grid (local GPS elevations from the ground gravity survey?) and your regional correction DEM (SRTM or other regional?) grid. The "grid properties" tool can be used to look at both grid cell sizes from your two DEM grids being used to create the TC grid, and used to look at the total number of cells in your input grids. It can also be used to look at the same properties of your large 250 mb TC grid. I'm guessing if the two input DEM grid cell sizes are set to reasonable numbers and if the regional DEM is a rectangle that is less than 400 km on a side, and TC optimization is set to faster, a new TC grid will be created in several minutes that will be quite a bit less than 250 mb in size and it should then be viewable. Before running the TC though the "scan XY" radio button at the bottom of the TC menu can be used to check the extent of your survey limits before the TC is run. You can also specify numbers into your outer and inner TC correction distances for more control in the TC menu. If nothing shows on your original large 250 mb output TC grid and the grid properties check indeed verifies there are TC numbers in the grid, you can try changing the color stretch to see if anything shows up after a linear, normal or equal area stretch is used, using either the default Geosoft color table or the Geosoft elevation color table. If the above does not help perhaps Geosoft could advise after they'd look at your input grids and data. Cheers, Ed Ed CunionRed Rocks Geophysical13224 W Utah CircleLakewood CO80228 USAcell 001-720-300-3641fax/phone 001-720-389-5224Skype ed.cunion On Monday, December 28, 2015 5:51 PM, author.nameemail <[email protected]> wrote: Hello, I created a very large terrain correction grid using the gravity module of Geosoft Oasis Montaj. It took over 3 days to create the terrain correction grid. Once it was done, it locked up my computer for another day and I finally had to shut it off. The TC grid is about 250 megs but if I open it in Oasis Montaj, it shows a blank screen. Is there any possibility that this grid may still be usable? If so, what do I need to do to make it show up on the screen. Secondly, every time I create large terrain correction grids, my computer locks up after it completes. What can I do about this? Anything? I often end up having to shut my computer down ungracefully and I do not like doing that. This is not an old machine, it is actually pretty new and powerful. Thank you for your help. Caitlin Bernier-GISPMagee Geophysical Services [email protected] --- Forum archives can be accessed here: http://lyris.geosoft.com/read/?fourm=geonet You are currently subscribed to geonet as: [email protected]. To subscribe or unsubscribe from any of our forums, select the User Forum selection on the Geosoft Community page: http://www.geosoft.com/support/community/forums/register/ --- Forum archives can be accessed here: http://lyris.geosoft.com/read/?forum=geonet You are currently subscribed to geonet as: [email protected]. To subscribe or unsubscribe from any of our forums, select the User Forum selection on the Geosoft Community page: http://www.geosoft.com/support/community/forums/register/ --- Forum archives can be accessed here: http://lyris.geosoft.com/read/?forum=geonet You are currently subscribed to geonet as: [email protected]. To subscribe or unsubscribe from any of our forums, select the User Forum selection on the Geosoft Community page: http://www.geosoft.com/support/community/forums/register/
