[GRASS-dev] discussion: replacing ps.map

[Trevor Wiens]

On Wed, 28 Mar 2007 23:08:59 +0100
Glynn Clements wrote:

> -- snip -- 
> To conduct such a test, generate a PostScript representation of a
> vector map using ps.map, then compare the time taken to render it to
> an image with "gs" against using d.vect with direct rendering.
> 

Method:
1. d.vect - create and render

Create shell script of d.mon start, d.vect, & d.mon stop commands

time ./displayscript.sh

2. ps.map - create psfile and display

a. Create ps.map file

time ps.map input=psmap.script output=testmap

b. display ps file

time gs -sDEVICE=x11 -dNOPAUSE testmap.ps -c quit

c. combined 

time ./comboshell.sh

Map 1 - raster & point file

1. d.vect 0.724s
2. ps.map 
	create   4.924s 
	display  0.441s
	combined 5.365s

Map 1a - map 1 without raster

1. dvect 0.366s
2. ps.map
	create   0.147s
	display  0.240s
	combined 0.380s

Map 2 - raster, vector lines & points

1. d.vect 0.765s
2. ps.map 
	create   4.878s
	display  0.546s
	combined 5.467s

Map 2a - map 2 without raster

1. d.vect 0.571s
2. ps.map
	create   0.195s
	display  0.346s
	combined 0.534s

Map 3 - raster, 2 vector areas using sql select for theme, lines, &
points

1. d.vect 1.143s
2. ps.map
	create   5.933s
	display  0.749s
	combined 6.313s

Map3a - same as map 3 without raster

1. d.vect 0.810s
2. ps.map
	create   0.346s
	display  0.557s
	combined 0.911s

These were done once, not many times but it does provide some
information. 

For vector only data, ps rendering would be a viable alternative to the
current display architecture. However for raster imagery the creation
of postscript files is painfully slow. I don't know if there is a way
to improve on this, but perhaps it is possible to adjust the resolution
of the raster image within the postscript file such as the -D
parameter used in dvips.

T
-- 
Trevor Wiens 
twiens at interbaun.com

The significant problems that we face cannot be solved at the same 
level of thinking we were at when we created them. 
(Albert Einstein)