[GRASS-user] i.rectify - how long is too long

[Luis E Menoyo]

It looks like i.rectify processes the complete target area instead of just 
the image area to be rectified.

If I want to restrict the calculations to the area of interest, can I use 
r.mask or should I create a target location of only the area of interest?

I would rather use r.mask, since I could change the mask depending on the 
area of interest.  If that won't work, then I will create subset locations 
for each image or flight line. 

Thanks to Giovanni and Moritz.  Your information is what leads me to 
believe that I must restrict calculations to the area of interest in order 
to make better use of computing resources. 

x-y location

g.region -p

projection: 0 (x,y)
zone:       0
north:      4171
south:      0
west:       0
east:       3280
nsres:      1
ewres:      1
rows:       4171
cols:       3280
cells:      13680880


Target location

g.region -p

projection: 1 (UTM)
zone:       4
datum:      nad83
ellipsoid:  grs80
north:      2401345.47908
south:      2350807.60197392
west:       574439.74229936
east:       640164.771271
nsres:      1.2962086
ewres:      1.29619826
rows:       38989
cols:       50706
cells:      1976976234


Luis E. Menoyo
U.S. Geological Survey
677 Ala Moana Blvd., Suite 415
Honolulu, HI  96813
lemenoyo at usgs.gov
808-587-2428



Moritz Lennert <mlennert at club.worldonline.be> 
01/19/08 10:32 AM

To
Luis E Menoyo <lemenoyo at usgs.gov>
cc
grass-user at lists.osgeo.org
Subject
Re: [GRASS-user] i.rectify - how long is too long






On 19/01/08 00:25, Luis E Menoyo wrote:
> 
> I'm using 1st order and 13 GCPs on an image and i.rectify has been 
> running over 3 hours.  Is the process locking up or is this amount of 
> time normal in image rectification?  Is i.rectify processing just the 
> area of the image to be rectified, of is it calculating for the whole 
> target mapset area?  In other words, should I have applied a mask to the 

> target mapset before running the georectify tool in order to cut down on 

> processing time?

What are your region settings in the target location, especially the 
resolution ? This can make an enormous difference in terms of 
calculation time.


Moritz

> 
> Any info would be greatly appreciated.
> Thanks!
> 
> Image info:
> 
> 
+----------------------------------------------------------------------------+ 

> 
>  | Layer:    D-10 at PERMANENT                 Date: Fri Jan 18 08:17:14 
> 2008    |
>  | Mapset:   PERMANENT                      Login of Creator: me |
>  | Location: x-y 
>      |
>  | DataBase: /gis/oahu_flightlines                     |
>  | Title:     ( D-10 ) 
>      |
>  | Timestamp: none 
>      |
> 
|----------------------------------------------------------------------------| 

> 
>  | 
>      |
>  |   Type of Map:  raster               Number of Categories: 255 
>       |
>  |   Data Type:    CELL 
>       |
>  |   Rows:         4171 
>       |
>  |   Columns:      3280 
>       |
>  |   Total Cells:  13680880 
>       |
>  |        Projection: x,y 
>       |
>  |            N:       4171    S:          0   Res:     1 
>       |
>  |            E:       3280    W:          0   Res:     1 
>       |
>  |   Range of data:    min = 0  max = 255 
>       |
>  | 
>      |
>  |   Data Description: 
>      |
>  |    generated by r.in.gdal 
>      |
>  | 
>      |
>  |   Comments: 
>      |
>  |    r.in.gdal input="/gis/oahu_flightlines/D/D-10\   |
>  |    .jpg" output="D-10" 
>       |
>  | 
>      |
> 
+----------------------------------------------------------------------------+ 

> 
> 
> Computer:
> 
> Mac Pro 2.66GHz, 2 dualcore Intel Xeon (4 cores total), 4Gb RAM
> 
> GRASS:
> 
> GRASS 6.3.0RC4 (2008)
> 
> 
> 
> Luis E. Menoyo
> U.S. Geological Survey
> 677 Ala Moana Blvd., Suite 415
> Honolulu, HI  96813
> lemenoyo at usgs.gov
> 808-587-2428
> 
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> grass-user mailing list
> grass-user at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/grass-user

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