This question is directly related to my previous one, in which I described the overall visualization that I'm trying to achieve.
I've managed to create a display of my raster data that looks more or less like I want, i.e. masked with the appropriate vector and color mapped. It occurred to me that if I could create a raster with an alpha channel using the mask, such that the areas that are masked become null or no value pixels, then I might be able to use r.blend with that raster and my base map raster to get the effect that I'm trying for.
I also have no idea how the d.* and r.* modules deal with alpha channels and would welcome some direction to appropriate documentation.
Cheers,
Gregory
If I understand your goal, what you want to do is switch the order of the operations a bit. Create your mask from the species range map before you do the blend, and then make a new raster of the heat map using r.mapcalc (i.e. r.mapcalc heat_masked = heat). Now remove the mask. THis will leave you with a masked head map, and the original basemap unmasked. And now do the r.blend. The masked out areas of the heat map will be null, and not affect the basemap, and those areas inside the mask will have the heat values, and thus get blended with the basemap. Finally add your administrative vectors, and you’re done. One point troubles me in your description of the problem. You want “clean curves” at the boundary of the mask, even though the heat raster has a large resolution. IIUC, this won’t work. The only way to achieve smooth curves is to resample the heat raster at a smaller resolution. Or alternatively to convert it to a vector polygon layer, using the “-s” flag for r.to.vect (smooth boundaries).
···
On 10/05/2013 01:17 AM, Gregory Penn wrote:
This question is directly related to my previous one, in which I described the overall visualization that I'm trying to achieve.
I've managed to create a display of my raster data that looks more or less like I want, i.e. masked with the appropriate vector and color mapped. It occurred to me that if I could create a raster with an alpha channel using the mask, such that the areas that are masked become null or no value pixels, then I might be able to use r.blend with that raster and my base map raster to get the effect that I'm trying for.
I also have no idea how the d.* and r.* modules deal with alpha channels and would welcome some direction to appropriate documentation.
Cheers,
Gregory
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