<div dir="ltr"><div>As far as I see, the size of the output raster is equal to the input size with the gdaldem utility set.</div><div>With the viewshed approach, the size of the output raster is calculated according to the provided parameters (ie. the observer location and maxdistance), however it is a good idea to allow the user customize the output format is some way.</div><div><br></div><div>Best regards,</div><div><br></div><div>Tamas</div><div><br></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">Eli Adam <<a href="mailto:eadam@co.lincoln.or.us">eadam@co.lincoln.or.us</a>> ezt írta (időpont: 2019. szept. 30., H, 21:35):<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">On Mon, Sep 30, 2019 at 11:54 AM Even Rouault<br>
<<a href="mailto:even.rouault@spatialys.com" target="_blank">even.rouault@spatialys.com</a>> wrote:<br>
><br>
> On lundi 30 septembre 2019 20:10:38 CEST Tamas Szekeres wrote:<br>
> > Hi,<br>
> ><br>
> > I've implemented a viewshed algorithm a while ago, by utilizing a modified<br>
> > version of the algorithm published at<br>
> > <a href="https://www.asprs.org/wp-content/uploads/pers/2000journal/january/2000_jan_8" rel="noreferrer" target="_blank">https://www.asprs.org/wp-content/uploads/pers/2000journal/january/2000_jan_8</a><br>
> > 7-90.pdf<br>
> ><br>
> > With this approach, it was crucial to provide a fast real-time option for<br>
> > the viewshed calculation on relatively large raster DEMs by using only a<br>
> > small memory footprint.<br>
> ><br>
> > The implementation can be found here:<br>
> ><br>
> > <a href="https://github.com/szekerest/gdal/blob/viewshed/gdal/alg/viewshed.cpp" rel="noreferrer" target="_blank">https://github.com/szekerest/gdal/blob/viewshed/gdal/alg/viewshed.cpp</a><br>
> > <a href="https://github.com/szekerest/gdal/blob/viewshed/gdal/apps/gdal_viewshed.cpp" rel="noreferrer" target="_blank">https://github.com/szekerest/gdal/blob/viewshed/gdal/apps/gdal_viewshed.cpp</a><br>
> ><br>
> > Does it make sense to spend some more effort and incorporate this approach<br>
> > in GDAL officially?<br>
><br>
> Sounds useful to me !<br>
> (old memories of having implement line-of-sight based intervisibility<br>
> algorithm in a past life !)<br>
<br>
Gdaldem (although it has a different history) has an assortment of DEM<br>
based utilities, <a href="https://gdal.org/programs/gdaldem.html" rel="noreferrer" target="_blank">https://gdal.org/programs/gdaldem.html</a>  I'm not sure<br>
if it would make sense there or elsewhere.  It would be a useful tool.<br>
<br>
Best regards, Eli<br>
<br>
<br>
<br>
><br>
> Even<br>
><br>
> --<br>
> Spatialys - Geospatial professional services<br>
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