Wolfgang Schwanghart

Last seen: 2 days ago | Active since 2007

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Professional Interests: GIS, Physical Geography, Hydrology, Geomorphology

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Does imread read subsets from cloud-optimized geotiffs
Hi, cloud-optimized geotiff (COG) is a format to work with spatial raster data in the cloud (https://www.cogeo.org/). I am curr...

2 years ago | 1 answer | 0

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Plot line with points at given distance
Since you are working with TopoToolbox, you might want to use the function getlocation. If you have a STREAMobj S, then you can ...

3 years ago | 0

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Inverse distance weighting based on direction
Hi Christian, interesting question. First of all, if you follow the IDW-approach, you might save a lot of computing time using ...

3 years ago | 0

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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...

5 years ago | 3 answers | 0

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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...

5 years ago | 0

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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...

6 years ago | 0

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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...

10 years ago | 0 answers | 1

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

12 years ago | 0

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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 ...

12 years 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...

12 years ago | 0

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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/...

13 years ago | 0

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image toolbox help
type doc images in the command window.

13 years ago | 0

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

13 years ago | 0

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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>...

13 years ago | 1

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

13 years 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...

13 years 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. [...

13 years 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...

13 years ago | 0

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

13 years ago | 0

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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...

13 years ago | 1

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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...

13 years ago | 1 answer | 0

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

13 years ago | 0

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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? ...

13 years ago | 1

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

13 years ago | 1

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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...

13 years ago | 0

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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...

13 years ago | 0

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correlation coefficient
Hi, doc corrcoef Best regards, W.

13 years ago | 1

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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://...

13 years 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...

13 years ago | 2

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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

13 years ago | 2

| accepted

Wolfgang Schwanghart

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