[GRASSLIST:9299] Re: strange behavior from v.to.points : feature or bug?

[Radim Blazek]

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
>
>