r.line stops partway through

[Olga Waupotitsch]

In info.grass.user you write:

>Who has used r.line to do raster -> vector conversion?
>I am trying to use it on a scanned contour separation.
>I am finding that it is working fine, but seems to stop
>part way down my data - ie I get ok results down to a
>certain row, and then nothing lower.  During running I get
>a load of lines saying things like

>> .
>> .
>> .
>> update_list:  isolated cell (284,357)
>> update_list:  isolated cell (288,71)
>> update_list:  isolated cell (289,356)
>> crowded cell 5H (301,723) -continuing
>> crowded cell 5H (321,852) -continuing
>> update_list:  isolated cell (353,732)
>> update_list:  isolated cell (353,800)
>> update_list:  isolated cell (360,903)
>> update_list:  isolated cell (363,687)

>and then it stops - apparently the last row processed is around 363.

>Is there some limit to the number of entries that it will
>take in the "update_list" which is not described
>in the man page?  Why am I only getting partial success?
>How can I remove the "isolated cells" prior to running
>r.line?  (Do I have to resort to r.mapcalc for morphological
>operations other than those offered by r.thin and r.grow?)

>(The map is very busy, and some of the contours are so
>close together that they merge in the scanned image.  As
>it is a karst area, there are lots of wierd features and
>sink holes also shown on the contour layer.  I was hoping to
>be able to do the cleaning up in v.digit as I find d.rast.edit
>a bit clunky.)

>Thanks

>Simon Cox
>----
>___________________________________________________
>      __  L     Dr Simon Cox			
>   ,~'  L_|\    VIEPS Department of Earth Sciences, 
>,-'         \   Monash University, Clayton Vic 3168        
>(            \  Australia
>\    ___     /          Phone +61 3 565 5762
> L,~'   "\_x/           Fax   +61 3 565 5062
>           u    simon at cerberus.earth.monash.edu.au
>___________________________________________________

The isolated points are not the problem. The problem (and the reason it stops)
are the crowded cells. At least from my own experience.
Did you run r.thin (a program recently rewritten by me :)
prior to using r.line?
Olga