[udig-devel] How to create a grid of features in a polygone

[andrea antonello]

Hi Ingmar,
now I see your problem...

> Good idea with to intersection of the horizontal and vertical lines.
>  But how do i create the lines with the constant spacing?
>
>  i manged to get the envelope from a polygone with 5 coordinates likes
>  this:
>
>  (13.68264407681451, 53.818121066825206, NaN)
>  (14.101893321395334, 53.818121066825206, NaN)
>  (14.101893321395334, 54.112935604110326, NaN)
>  (13.68264407681451, 54.112935604110326, NaN)
>  (13.68264407681451, 53.818121066825206, NaN)
>
>  a nice bounding box. and now?
>
>  the first horizontal line is
>
>  (13.68264407681451, 54.112935604110326, NaN) (14.101893321395334,
>  54.112935604110326, NaN)
>
>  the upper left corner to the upper right corner. how do i get the next
>  point for the Y coordinate with a distance of, lets say, 200m?
>
>  (13.68264407681451, ??, NaN) (14.101893321395334, ??, NaN)

You are dealing with lat-long coordinates, so it doesn't make sense to
talk metric.
You could say: "...point for the Y coordinate with a distance of, lets
say, 60'?"
If you need metric, you should first reproject the layer into your
local metric system and then do maths with your metric coordinates.

Is that the problem you have?

Ciao
Andrea



>
>  Thanks again. Ingmar
>
>  Am 30.03.2008 um 15:21 schrieb andrea antonello:
>
>
> >> i have a little "geospatial" question. I want to draw polygones on a
>  >> polygone layer and then start a wizard which fills the polygone with
>  >> features (with a point geometry). All features have the same distance
>  >> (lets say 100m to each other) and all are in the area of the
>  >> polygone.
>  >>
>  >> Sounds like a not so difficult problem, but i hope that there is a
>  >> nice way to program this. perhaps i should use the gridcoverage
>  >> class?
>  >> i realy dont know where to start.
>  >
>  > Hi Ingmar,
>  > I think it is more a JTS related question.
>  > What I would probably do (I'm writing as I'm thinking) is to create
>  > the grid of lines at the wanted distances one from the other.
>  > The horizontal lines and vertical lines should stay in two different
>  > multilinestring geometries. Then through
>  >
>  > resultPointGeom = horizontalLines.intersection(verticalLines)
>  >
>  > you gain all the points you wanted to have into the resulting
>  > geometry.
>  > After that you will have to get from those only the ones inside the
>  > polygon, which I assume can be done through another intersection
>  > between polygon and resultPointGeom.
>  >
>  > Ciao
>  > Andrea
>  >
>  >
>  >
>  >>
>  >> Thanks for any advice.
>  >>
>  >> Greats Ingmar
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