Hi Adrian,
This is the approach I used to calculate SVF in GRASS (as you probably know).
You can test the similarity to Kokalj et al's original algorithm by processing
another copy from your DTM using their ENVI plugin or standalone tool from here
http://iaps.zrc-sazu.si/en/svf#v and running some visual or quantitative
assessments
FWIW I can't remember if I did a quantitative comparison of the horizon images
I created against the SFV I made from teh standalone (for me it was sufficient
that the process and variables of horizon view creation in GRASS were
methodologically the same as the published SVF, and visually they were
identical)
Good luck!
Rebecca
>________________________________
> From: Adrian Kirilov <[email protected]>
>To: Hamish <[email protected]>
>Cc: GRASS user list <[email protected]>
>Sent: Sunday, 19 May 2013, 13:57
>Subject: Re: [GRASS-user] Fwd: Airborne LiDAR data strip adjustment
>
>
>
>I applied the same method actually (after a bit thinking and reevaluation of
>my first idea). I prefer to use v.in.ascii -t -r -z input= fs= z= out= ,
>because I'm interpolating the points with v.surf.bspline (bilinear, to be more
>precise) afterwards.
>
>
>I have some more questions now. Sorry, but I don't know if I should put them
>in a different e-mail and subject...
>
>
>I used r.horizon module to build horizon view for 16 directions, consequently
>I received as a result 8 output raster maps:
>r.horizon elevin=demb30_5_combined@FlemishArdennes direction=0 horizonstep=45
>maxdistance=10 horizon=SVF_demb30_5
>
>
>
>After that I combined them witn r.mapcalc but with simple addition only:
>
>
>
>r.mapcalc:
>'SVF_demb30_5_0@FlemishArdennes + SVF_demb30_5_1@FlemishArdennes +
>SVF_demb30_5_2@FlemishArdennes + SVF_demb30_5_4@FlemishArdennes +
>SVF_demb30_5_5@FlemishArdennes + SVF_demb30_5_6@FlemishArdennes +
>SVF_demb30_5_7@FlemishArdennes'
>
>
>Is this approach correct?
>
>
>And how can I change the range value of the output raster after I have set up
>first color table with r.colors color=grey. I want to change the range from
>0.0-1.0 to something else, like 0.7-1.0 for example to get more contrast or
>brightness. The last is in fact the question from my first e-mail (see up)
>with this subject.
>
>
>Thanks a lot for the help!
>
>
>
>
>Greetings,
>
>
>Adrian Kirilov
>
>
>
>On Sat, May 18, 2013 at 5:37 AM, Hamish <[email protected]> wrote:
>
>Adrian wrote:
>>> It's a series of points. But how can I export them from all
>>> imported files (strips) later into a single one ASCII file into
>>> specific region? I think that v.out.ascii for example is only
>>> for exporting single file. And I need to export multiple,
>>> falling into the region. Is this possible in GRASS?
>>
>>first set the region and grid size with g.region, check it is
>>ok with the -p flag.
>>
>>then depending on what you want to do:
>>
>>cat *.asc | r.in.xyz x= y= z= fs= input=- output=mapname method=
>>
>> or
>>
>>cat *.asc | v.in.ascii -r -bt x= y= z= fs= output=mapname
>>
>>
>>r.in.xyz discards points outside of the current region, as does
>>v.in.ascii if you use the -r flag.
>>
>>
>>
>>if your data is already processed, sorted, and cleaned I'd
>>go straight for r.in.xyz myself, but that's just me.
>>
>>
>>Hamish
>>
>
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>
>
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