[GRASSLIST:9303] Re: strange behavior from v.to.points : feature or bug?

[Dylan Beaudette]

Hi Radim,

Thanks for the pointers. Maybe a hint about this in the documentation 
would be helpful, in case that I am not the only who gets mixed up with 
this module.

Cheers,

Dylan

On Dec 5, 2005, at 4:28 AM, Radim Blazek wrote:

> Hi,
>
> I would say it is correct. At least what I intended.
> dmax is realy maximum limit not exact ditance.
>
> If you need points on exact distance from the beginning
> you should use v.segment.
>
> Radim
>
> On 12/4/05, Dylan Beaudette <dylan.beaudette at gmail.com> wrote:
>> Noticed something strange in v.to.points in GRASS61-CVS (current)
>>
>>
>> vector 't1' is 1000 meters long
>>
>> #this should extract 11 points, each 100 meters apart
>> v.to.points -i in=t1 out=t1_points dmax=100
>>
>> resulting table:
>> +------+------+------------------+
>> | cat  | lcat | along            |
>> +------+------+------------------+
>> |    1 |    1 |                0 |
>> |    2 |    1 | 90.9090909090943 |
>> |    3 |    1 | 181.818181818189 |
>> |    4 |    1 | 272.727272727283 |
>> |    5 |    1 | 363.636363636377 |
>> ...
>> |   11 |    1 | 909.090909090943 |
>> |   12 |    1 | 1000.00000000004 |
>> +------+------+------------------+
>>
>> notice that each point is about 90 meters apart, and there are 12
>> points.
>>
>> now when i run v.to.points with dmax=110 :
>> #this should extract 10 points, each 110 meters apart
>> v.to.points -i in=t1 out=t1_points dmax=110
>>
>> resulting table:
>> +------+------+------------------+
>> | cat  | lcat | along            |
>> +------+------+------------------+
>> |    1 |    1 |                0 |
>> |    2 |    1 | 100.000000000004 |
>> |    3 |    1 | 200.000000000007 |
>> ....
>> |   10 |    1 | 900.000000000034 |
>> |   11 |    1 | 1000.00000000004 |
>> +------+------+------------------+
>>
>> the correct and desired result!
>>
>> Any ideas on this {feature,bug} ?
>>
>> Thanks,
>>
>> --
>> Dylan Beaudette
>> Soils and Biogeochemistry Graduate Group
>> University of California at Davis
>> 530.754.7341
>>
>>
>
>
--
Dylan Beaudette
Soils and Biogeochemistry Graduate Group
University of California at Davis
530.754.7341