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Wolfgang Schwanghart


Last seen: 7 dagar ago |  Active since 2007

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Professional Interests: GIS, Physical Geography, Hydrology, Geomorphology

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Question


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...

mer än 2 år ago | 1 answer | 0

1

answer

Answered
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 ...

nästan 3 år ago | 0

| accepted

Answered
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 ...

nästan 3 år ago | 0

| accepted

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...

ungefär 5 år 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...

nästan 6 år 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...

mer än 6 år 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...

nästan 11 år 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.

mer än 12 år 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 ...

mer än 12 år ago | 0

Answered
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...

mer än 12 år 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/...

ungefär 13 år ago | 0

Answered
image toolbox help
type doc images in the command window.

mer än 13 år ago | 0

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

mer än 13 år 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>...

mer än 13 år ago | 1

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

mer än 13 år ago | 0

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

mer än 13 år ago | 0

Answered
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. [...

mer än 13 år ago | 0

Answered
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...

mer än 13 år 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/> ...

mer än 13 år 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...

mer än 13 år ago | 1

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...

mer än 13 år 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...

mer än 13 år 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? ...

mer än 13 år 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> ...

mer än 13 år 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...

mer än 13 år 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...

mer än 13 år ago | 0

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

mer än 13 år 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://...

mer än 13 år ago | 1

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

mer än 13 år 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

mer än 13 år ago | 2

| accepted

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