[GRASS5] g3d notes and possible bugs
John Harrop
johnh at sjgeophysics.com
Fri Jan 10 20:28:23 EST 2003
Now the recent panic for getting products out is over I've had a chance
to look at the cause of the problem a little more. If I narrow down the
region and make it completely sub-surface, the program completes
without any problems. We are working with a medium size regular block
model 134x90x60 with cells of varying size. Some of the cells, perhaps
10%, are air and have null values. I've tried with and without the air
blocks. I would prefer to exclude them from the site file altogether,
but I thought that perhaps s.vol.rst was failing when it tried to
interpolate in a region of all or mostly air.
I'm now trying a 20x95x45 block well inside our data, which currently
includes -1 values for air cells. (All subsurface values are positive).
The processing reaches about 26% before failing with a segmentation
fault. I may well be failing to set some parameters correctly, but that
shoudl not be causing a segmentation fault.
I gather from the man page that s.vol.rst is not doing 3d masking, but
rather projecting a 2d mask through all the depths. Is there a way to
mask cells above the surface?
Command line and messages follow:
-----------------------------------------
s.vol.rst input=block3.chg elev=rst.test.2
Warning: some points outside of region -- will ignore...
Warning: strip exists with insufficient data
Processing all selected output files
will require 7600 bytes of disk space for temp files
Warning: there are points outside specified region--ignored 450036 points
Percent complete:
Warning: taking too long to find points for interpolation--please change
the region to area where your points are
Segmentation fault
-----------------------------------------
Regards,
John Harrop
Helena wrote:
>>3) Importing 2d elevation data does not result in the same display as
>>importing equivalent data with a 3d site approach. I'm fairly sure the
>>fault lies in s.vol.idw - (yes, I know it was recommended that we use
>>s.vol.rst, but I have yet to get the 3d one to run without crashing.)
>>
>>
>
>do you use the 5.0.0 version or the one in exp ? Where does it crash and
>what
>it says? It used to run OK although Jaro recently reported that the
>version
>in the 5.0.0 release gives segmentation fault if the sites
>are not exactly in the format x|y|z|#n %value (for example sites
>x|y|z|%value
>make it crash with segmentation fault which is obviously a bug but we
>did not have
>time to look into it).
>
>thanks,
>
>Helena
>
>
>
>> For a smooth 3d block model the idw approach is good enough for
>>testing. Both Z (elevation) and Y (northing) are reversed when
>>displayed after importing. With the storage order being the reverse of
>>physical coordinates for Y and Z its not hard to accidentally reverse
>>the storage in a loop. I think AV may have done two fixes in the code
>>that cancelled each other ;-) I'll check that in more detail and report
>>later.
>>
>>
>>
>
>
>
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