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Wolfgang Schwanghart


University of Postdam

Last seen: 5 dagen ago Active since 2007

Professional Interests: GIS, Physical Geography, Hydrology, Geomorphology

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Question


Fit Gaussian mixture model with weighted observations
Hi everyone, looking at the help of fitgmdist, I cannot see that there is the possibility to weight observations. Is there a rea...

ongeveer 2 jaar ago | 3 answers | 0

3

answers

Answered
2D gaussian filter with a variable sigma
Hi Chad, below is some code that does the trick using nlfilter. To be more efficient, I created a look-up table with a finite s...

meer dan 2 jaar ago | 0

Answered
What makes a Toolbox a Toolbox, and how is it recognized by Matlab?
Hi Chad, the trick is to have a Contents.m-file in the main folder of your toolbox. In TopoToolbox, the file starts with T...

meer dan 3 jaar ago | 0

Question


Customized icons in workspace
Hi all, I have written a couple of MATLAB classes and, as icing on the cake, I'd like to have customized icons in the worksp...

meer dan 7 jaar ago | 0 answers | 1

0

answers

Answered
total number of elements which are not zero
Hi, what about: B = sum(Percey~=0,2); Regards, W.

meer dan 9 jaar ago | 0

| accepted

Answered
How can I perform a comparison function (of surrounding pixels) on a DEM using a starting pixel?
Hi, you might be interested in using the function ixneighbors available on the FEX which might make life a little easier for ...

meer dan 9 jaar ago | 0

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Connected graph given adjacency matrix
You can use the function dmperm to see if a graph consists of one or several connected components. E.g. see the example here <h...

meer dan 9 jaar ago | 0

| accepted

Answered
path elevation profile
Hi, if you have the image processing toolbox, the function improfile should do what you ask for. <http://www.mathworks.de/help/...

bijna 10 jaar ago | 0

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image toolbox help
type doc images in the command window.

ongeveer 10 jaar ago | 0

Answered
plotting more data from large data
Hi doc gscatter hope this helps. Regards, W.

ongeveer 10 jaar ago | 0

Answered
What does +(A>0) do?
I often do this to convert a logical matrix to double. However, I just tried and realized that this is slower than A = double(A>...

ongeveer 10 jaar ago | 1

Answered
error using imsubtract
Hi Megah, apparently both variables don't have the same class. Try image3 = imsubtract(im2double(image1),im2double(BWfinal)...

meer dan 10 jaar ago | 0

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Calculate the indirect distance between two points
Bahare, you might find this contribution interesting: <http://www.mathworks.com/matlabcentral/fileexchange/8625-shortest-pat...

meer dan 10 jaar ago | 0

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Ordered connected components
Hi Dustin, I don't have MATLAB at hand right now, so I cannot try, but I think bwboundaries should solve your problem. [...

meer dan 10 jaar ago | 0

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Graph analysis question
I just tried your example. While results of a kmeans clustering don't look too promising, the function clusterdata works quite w...

meer dan 10 jaar ago | 0

Answered
Overlay digital elevation model on hillshade
Hi Ajay, you might want to check TopoToolbox, which includes such a function. <http://physiogeo.unibas.ch/topotoolbox/> ...

meer dan 10 jaar ago | 0

Answered
Count black and white pixels on a image
How about using *blockproc* to get the number of white pixels (in case you have the image processing toolbox)? A = full(spran...

meer dan 10 jaar ago | 0

Question


Keeping k largest values in each column of a sparse matrix
Hi everyone, I am trying to implement an algorithm that involves a pruning of a large sparse matrix. The pruning scheme shoul...

meer dan 10 jaar ago | 1 answer | 0

1

answer

Answered
data correction
Hi, you can identify the NaNs using the function isnan. I = isnan(dem); % where dem is the digital elevation model The inpa...

meer dan 10 jaar ago | 0

Answered
Problem on fuzzy inference calculations ..
Hi, the error message says all: The first input must be a defined DOUBLE matrix Is the variable input in double format? ...

meer dan 10 jaar ago | 1

| accepted

Answered
finding neighbor of a position
Hi, you might find this function useful. <http://www.mathworks.com/matlabcentral/fileexchange/16991-neighbor-indexing> ...

meer dan 10 jaar ago | 1

Answered
Connect bwlabeled components
I'd start with using the function bwlabeln to label the connected components in the 3d. This, however, requires them to never ov...

meer dan 10 jaar ago | 0

Answered
straighten curved Image
This is not trivial and I think you should show what you have done so far. If you haven't really started yet, you may want to lo...

meer dan 10 jaar ago | 0

Answered
correlation coefficient
Hi, doc corrcoef Best regards, W.

meer dan 10 jaar ago | 1

| accepted

Answered
how to draw a grid in MATLAB???
Hi, take a look at Steve's blog, where he describes how to generate a pixel grid. Perhaps, this is what you want. <http://...

meer dan 10 jaar ago | 1

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Kriging
To my knowlegde there is no comprehensive geostatistical software written in Matlab. I would always use packages such gstat or g...

meer dan 10 jaar ago | 2

Answered
How to plot a 2D vector-field and exclude zero-vectors (dots) in the graph?
How about: I = ~(T(:,3)==0 & T(:,4)==0); quiver(T(I,1),T(I,2),T(I,3),T(I,4)); cheers, Wolfgang

meer dan 10 jaar ago | 2

| accepted

Answered
Is there a way to prevent or circumvent the formation of long edges in a Deluanay Triangulation?
Hi AJP, without knowing what exactly yoou want to do, I like to link to a tool that was extremely helful to me. <http://w...

meer dan 10 jaar ago | 0

Answered
TSP using GA
If this is so urgent for you, did you anything to find available code? Apparently not. Searching google with "tsp matlab ga" dir...

meer dan 10 jaar ago | 0

Answered
Edge direction
Hi, to extract edges of any direction, you just need to choose the right structuring element for a morphological opening. E....

meer dan 10 jaar ago | 3

| accepted

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