[QGIS-Developer] GRASS r.walk

[Joshua Quesenberry]

Is it normal for an r.walk over an area of 10,500 acres to use up 12GB of HD
space and want more? That's using up every bit of space I have left, so it's
crashing out. I tried setting the maximum cost to 10 and I think 1 also, but
the algorithm keeps running for a long time making these really large files.

 

Thanks,

 

Josh Q

 

From: Joshua Quesenberry [mailto:engnfrc at gmail.com] 
Sent: Thursday, November 23, 2017 12:05 PM
To: qgis-developer at lists.osgeo.org
Cc: engnfrc at gmail.com
Subject: GRASS r.walk

 

Happy Thanksgiving Everyone!

 

Who's very familiar with GRASS r.walk? I'm finding some tutorials and man
pages with examples but having trouble applying what I've found. I'm trying
to create mobility models for use with lost person analytics.

 

Does is matter what format the input layers are in? Should they all be UTM
since that's in meters? Or is it smart enough to mix and match WGS84 and UTM
layers? And along the same lines, does my DEM need to have cells in meters?
Most of what I get comes native in WGS84 with altitudes in feet, so if I
don't need to add extra steps converting to UTM and cells to meters that's a
good thing.

 

For the friction layer, the example on the man page appears to use
landclass96 and only has 7 classifications. the NLCD 2011 land
classification file I have has 30-40 classifications ranging from 11 to 95,
does anyone have friction costs that can be applied to this data? Or at the
very least some idea of the best method to use to come up with those values
myself?

 

Thanks!

 

Josh Q

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