ImportAGN, SubstractFeature from Shapefile, ExportAGN possible?

[roland_lfor]

Hi,

I'm trying to process big areas in 2 passes for memory constraints, then I tried to subtract roads to vegetation AGNs already build during a 1st pass. I think it's not working, so maybe I'm wrong on the method.
I verified that some AGN files are effectively modified after the process (from date/time tag).

The steps are below:

#
IMPORTOGR|D:\Roads.shp|*|*|AUTODETECT
#
# extrude roads
LineToPolygon|FTYPE="LINE" and fclass="motorway" and tunnel<>"T"|25|String;polygons|roadpoly
#
# Free memory
UnloadFeatures|FTYPE="LINE"
#
# Import vegetation AGN
ImportAGN|D:\VEG|CREATEFEATURES
#
# Substract road polygons from vegetation
SUBTRACTFEATURES|*|polygons="roadpoly"|1.0
#
# Free memory
UnloadFeatures|polygons="roadpoly"
#
SplitGrid|AGN|*
#
# Save modified AGN
ExportAGN|P3D v2|D:\VEG

Thanks

Roland

 

[arno]

Hi,

I don't see a SplitGrid step. So that means your roads and imported agn files are probably in different grid cells.

 

[roland_lfor]

Hi Arno,
There is a SplitGrid step before ExportAGN.
Actually if I forget SplitGrid command, ScenProc script parser raises an error.

However do you mean the SplitGrid step must be done before Substract? Before ImportAGN or after?

 

[arno]

It should be before the subtract step. Probably best to put it directly after the ImportOGR.

 

[roland_lfor]

Thanks Arno, you are the man as usual

 

[roland_lfor]

I continued my tests and unfortunately the SubstractFeatures() from loaded AGN still does not work.

I have added attributes to my vegetation AGNs so I'm sure that the SubstractFeature applies to the vegetation.
I compare the byte sizes of my AGN folder before and after, and as they are perfectly equal I'm pretty sure the script did not modify anything.

Here is how the script looks like now:

# Import roads lines
IMPORTOGR|D:\Roads.shp|*|*|AUTODETECT
#
# Import vegetation AGN
ImportAGN|D:\VEG|CREATEFEATURES
AddAttribute|FTYPE<>"LINE"|String;polygons|vegpoly
#
# extrude roads along fclass
LineToPolygon|FTYPE="LINE" and fclass="motorway" and tunnel<>"T"|25|String;polygons|roadpoly
LineToPolygon|FTYPE="LINE" and fclass="trunk" and tunnel<>"T"|25|String;polygons|roadpoly
LineToPolygon|FTYPE="LINE" and fclass="primary" and tunnel<>"T"|15|String;polygons|roadpoly
LineToPolygon|FTYPE="LINE" and fclass="secondary" and tunnel<>"T"|12|String;polygons|roadpoly
LineToPolygon|FTYPE="LINE" and fclass="tertiary" and tunnel<>"T"|10|String;polygons|roadpoly
#
# Free memory
UnloadFeatures|FTYPE="LINE"
#
SplitGrid|AGN|*
#
# Substract road polygons from vegetation
SUBTRACTFEATURES|polygons="vegpoly"|polygons="roadpoly"|1.0|MINAREAPOLY
#
# Save
ExportAGN|P3D v2|D:\VEG

 

[roland_lfor]

Well, I'll find another way to do that. I think it's not possible this way.
Let's go around the obstacle

 

[arno]

Hi,

After you subtract the polygons you need to create new agn polygons. The subtract works on the features, not on the agn.

But I guess you then need a way to unload the original agn first and that option is probably not there now.