Re: [libreoffice-users] Re: Filter algorithm question

At 09:06 24/02/2015 -0700, Nobody Noname wrote:
> If I create a list of Y-values for the shape boundary for each 
> X-coordinate in the grid I end up with:
>
> Y-value of the shape boundary             Corresponding X-coordinate 
> of the grid
> 9,10,11,12,13,14                                        7

Does this mean that the shape is re-entrant and that 9 to 10, 11 to 
12, and 13 to 14 are inside? Well, that's the same as saying that 9 
to 14 is inside, and you need better resolution of your grid if you 
are to treat the shape appropriately. Note that it may be the case 
that if you chose, arbitrarily, to list the boundary X-values for 
each Y-value instead, it's possible that your shape might not be 
re-entrant and the shape could be expressed more simply.

> ...
> 6,11,12,17                                                  12
> ...
>
> If I now look at my list of bird coordinates and take one example of 
> a birds X-coordinate being 12, its within the ranges of the shape 
> boundary Y-values above, but if I check its position (at X=12, Y=19) 
> I can see its not within the boundary. So I'm still missing something.

Again, if this means that 6 to 11 and 12 to 17 are within the shape, 
then that is the same as 6 to 17 and you need better resolution. But 
in any case, a Y-value of 19 is clearly outside the 6 to 17 range for 
X=12, which coincides with your claim that this bird is outside the 
shape. No problem.

Are you perhaps confusing X and Y?

Brian Barker  


--
To unsubscribe e-mail to: users+unsubscribe@global.libreoffice.org
Problems? http://www.libreoffice.org/get-help/mailing-lists/how-to-unsubscribe/
Posting guidelines + more: http://wiki.documentfoundation.org/Netiquette
List archive: http://listarchives.libreoffice.org/global/users/
All messages sent to this list will be publicly archived and cannot be deleted