Problem with point-KDE

[Tanja]

Dear Stefan,

I recently installed openJUMP with HoRAE and now I want to calculate home ranges with Point KDE but have some troubles with it. I'm using a dataset, which I loaded from a shape-file (since I've been using ArcGIS), but when I get to calculate the point KDE, calculation process is stopped after a few seconds and I only get to see the row at the bottom left of the window highlighted yellow, saying "no point dataset". I checked the geometry of my shapefile and it is point. I also checked the coordinate system, which is correct. I also tried the Line-based KDE with the same dataset and here calculation does work. Do you have an idea what the problem is?

Hope you can help me,

thanks in advance,

kind regards, Tanja

[Stefan Steiniger]

Hi Tanja,

my guess is that you are actually having a "Multi-point" dataset.
There are two options to check that,
a) you can send me a sample: for that select some points, and use
Edit>Replicate to copy them into a new layer, and then save the sample
dataset in whatever format and send it to me off-list : sstein -/at/-
geo.uzh.ch

b) if you open the attribute table of the layer (using the matrix
button), what symbol is shown in the very first column for the geometry
(before FID)? Is it a single dot or three dots? Three dots, means it is
multi point. You can also click on the symbol to know more.

If you have multi-point, then you can extract/transform them to single
points by (i) making the layer editable, (ii) selecting all points
(Edit>Select>Select all points from layer) (iii) right-mouse click in
the map window and chose "explode" selected objectes (in german it would
be "zerlegen").

However, it could be also that only one of your points is of a different
type (or not a point). In that case you would see that based on the symbol.

let me know, if any of this helps,
stefan

Am 11.03.13 06:25, schrieb Tanja:

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[sonjab...@googlemail.com]

Dear Stefan,

I have exactly the same problem with calculating the KDE_lscv. I'm using a point dataset as a shape-file. The calculation stops every time with the message 'no point dataset'.
With the ad-hock approach, there is no problem.

I checked my Data like u wrote above and I'm really sure about my single point data.

are there some other options I can check?

best regards
Sonja

[Stefan Steiniger]

Hi Sonja,

thanks for using OJ HoRAE.

First question: Did you use the latest HoRAE version (I fixed something
earlier this year with regarding to the Asymptote calculation)? And I
also don't really recommend using LSCV if you have more that 100-200
points (lets say 1000 or so) as the LSCV parameter calculation usually
fails (h will be too small).

I can't really say what the issue would be except by looking at the
data. Do you think you can send me the dataset as zipped shapefile
(which must include the shp, dbf and shx file)? Or did you import your
data from a csv? In this case, you really shouldn't have MultiPoints.
Btw. MultiPoints are single points but put into a collection (i.e. like
combine in PowerPoint), whereby this collection of points has the same
attributes. You can check if you have such MultiPoints in your dataset with
Edit > Select > Select by Geometry Type : and choose the MultiPoint
option.
If you actually have some, make the layer editable, have them (still)
selected and do a right-mouse click in the map window - then chose from
the mouse menu "Explode Selected Features"


best,
stefan