[GRASSLIST:3] Re: New GIS Manager adds transparency to layers

[Ian MacMillan]

Michael, I haven't tried this out yet, but it sounds excellent.  Cheers  
to all of your efforts to make GRASS more user-friendly for newbies.  I  
am going to feel less guilty about making my students use GRASS in  
their classes instead of Arc.

-Ian

On Mar 10, 2006, at 12:59 PM, Michael Barton wrote:

> I’ve just finished phase 2 of the GIS Manager update and it’s pretty  
> exciting. At first glance, it looks a lot like the one I’ve been  
> working on and have in the CVS now, but with a couple of important  
> exceptions. One is that transparency is now supported for all GRASS  
> layers.
>
>  The second will probably generate the most discussion, so I’m ready  
> to duck and run for cover.  Now GRASS is consistent with other GIS  
> programs and more intuitive (as much as I am skeptical about that  
> term) in that the uppermost layer in the layer tree is also the top  
> map in the display. Related to this, new layers insert directly above  
> the currently selected layer instead of at the bottom of the layer  
> tree.
>
>  The main changes come ‘under the hood’ of this version of the GIS  
> Manager. It uses g.pnmcomp to composite a set of maps (each rendered  
> as *.PPM files) into a visual display. One of the results is that now  
> GRASS is significantly faster in adding new layers, turning layers on  
> and off, and changing layer attributes—only the new or changed layer  
> needs to be rendered; the others will just be re-composited into a  
> display from existing PPM files. This all happens in a GRASS .tmp  
> directory, so that it doesn’t clutter up your home directories. The  
> other important thing about this new architecture is that it makes  
> GRASS even less dependent on the xdriver and PNGdriver for  
> visualization. GRASS can become more easily portable to different OS’s  
> and GUI frameworks. It is also more scriptable. You can write a script  
> that will create a complete, multilayered map, and output it to a  
> graphics file.
>
>  One consequencer of this new architecture is that the GIS Manager  
> does not currently support display output to PNG files. With GDAL  
> (required for many GRASS features) and ghostscript installed, it does  
> support output to PPM/PNM, TIF, JPG, BMP, EPS, and PDF.
>
>  Command line usage is still supported  in several ways—the old  
> xterminal is still there, there is the new command console, and you  
> can add command layers to the layer tree and display them.
>
>  You can see a screen shot of semi-transparent soil vector areas  
> overlaying a raster shaded relief map at
>
> http://www.public.asu.edu/~cmbarton/files/grass_screenshots/gism2-2.jpg
>
>  I’ve committed all changes to the CVS. For those of you with binary  
> versions of GRASS who would like to try it, I’ve posted packages you  
> can use to replace your current GIS Manager on my website. For full  
> functionality, you need a version of grass that is dated  
> 21-February-2006 or later. For those of you with a slightly earlier  
> version, I made a second package with all functionality minus  
> transparency. Here are the links.
>
>  New GIS Manager files
>
>   
> <http://www.public.asu.edu/~cmbarton/files/grass_gismgr/ 
> gism_rc4_20060307.tgz>
>
>  New GIS Manager files for people with recent, but pre-21 February  
> 2006 binaries.
>
> <http://www.public.asu.edu/~cmbarton/files/grass_gismgr/ 
> gism_rc4_20060307pre_02-21.tgz>
>
>  Enjoy
>  Michael
>
>  ______________________________
>  Michael Barton, Professor of Anthropology
>  School of Human Evolution and Social Change
>  Arizona State University
>  Tempe, AZ  85287-2402
>  USA
>
>  voice: 480-965-6262; fax: 480-965-7671
>  www: http://www.public.asu.edu/~cmbarton
>
 >
 >
What happens if a big asteroid hits Earth? Judging from realistic  
simulations involving a sledge hammer and a common laboratory frog, we  
can assume it will be pretty bad.
  - Dave Barry


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