I have a Matlab script that calculates a certain terrain-parameter (describing the theoretical shelter from and exposure to wind) based on a digital terrain model. The script works both in Matlab and Octave and yields a matrix.
Now: I am trying to couple this with a GRASS GIS shell script. I can call the script from GRASS, but I have problems getting the output back into GRASS. One way is to use the .mat format. The problem is, however: When I export the result of the calculation (with save -mat4-binary result.mat ans) and try to import the .mat file into GRASS, the error is:
ERROR: No 'map_data' array found in [...file]
Similarly, when I load the file in Octave and try to display it
load result.mat
imagesc(map_data), axis equal, axis tight, colorbar
the error is
error: `map_data' undefined near line 19 column 9
error: evaluating argument list element number 1
When I export from Matlab, it is the same problem.
Where is the bug?
Any help is greatly appreciated.
The "bug" is, your mat-file does not contain any variable named "map_data", I would guess your variable in the mat-file is named "ans". I would use res=load result.mat, then you get a struct with everything which is in the mat file. If you type in res. autocomplete should list all variables inside the struct (not sure about octave), alternatively use fieldnames(res) to list all variable names.
/Update:
I took a short look into the documentation of grass. It expects predefined variable names, all beginning with map_*. Instead of
save -mat4-binary result.mat ans
you should rename your variables to match the documentation and save them using
save -mat4-binary result.mat map_*
Related
I'm a beginner so sorry in advance for the mistakes.
I have a set of data from a camera recording saved in a 4D array with these dimensions (250x300x10603x12).
The first is the dimensions of the video (pixels). The 10603 are the FrameRatexTime. 12 are the subjects I recorded.
I extract one subject at a time for analysis in this way:
subj1 = data(:,:,:,1);
This brings me to an array containing the frames of subject 1, which I can display with implay.
Now I would like to write a video of this new array and save it in .avi format, I use this code:
v = VideoWriter('subj1.avi')
open(v)
writeVideo(v,subj1)
close(v)
but it keeps giving me this error
Error using VideoWriter/writeVideo (line 410) IMG must be an array of
either grayscale or RGB images.
In fact, looking at the shape of the array, there is nothing that points to a grayscale or RGB index. How can I get a .avi file in this case? Do I have to transform the array?
Why does it still display the video with implay?
clarification: the fact that I have to transform the array into an .avi file is because I will have to analyse it by exporting it to Python with OpenCv.
In fact, if I export the .mat file directly to Python, I can't get the list of Frames.
Matlab's documentation for writeVideo says that for a sequence of grayscale images like you have, it is expecting a "height-by-width-by-1-by-frames" array. You are only passing it "height-by-width-by-frames".
So, you need to reshape your subj1. Maybe try doing it like this:
newsubj = zeros(250, 300, 1, 10603)
newsubj(:,:,1,:) = subj1
and then save newsubj instead of subj1:
writeVideo(v,newsubj)
Finally, I think you may get some lossy compression when you save as an avi, so it may not be the best way to export it from Matlab and importing it to Python.
I am trying to write a script which loads the camera parameters from Meshroom and imports them into a CAD program. My first understanding was that these parameters (position, rotation matrix, focal length etc.) are contained in the JSON-file cameras.sfm in the StructureFromMotion-subdirectory.
After importing these parameters into Rhino3D and comparing the resulting views onto the 3D-mesh with the undistorted photographs in the PrepareDenseScene-directory, I find surprising large discrepancies. The mesh which was the result of the run was good, so I think that the deviation is because of the parameters in cameras.sfm being not the final ones. This assumption is also supported by the fact that the file only contains the focal length as read from the input images' EXIF information and no refined values. So my question is:
How can I access the final camera parameters from the output of Meshroom?
Knowing this would help me a lot for re-building a photogrammetry/CAD pipeline I had previously implemented for VisualSFM + CMPMVS.
Many thanks!
EDIT: As this is my first post, I am not able to create a new tag for Meshroom. Perhaps this could be added by someone else? Thanks!
I'm having trouble reading a .txt file to get some data. I want to be able to change some of the values this data contains.
At first, I used this:
A=importdata('myfile.txt');
And got this cell array:
Now what I want is this:
1) Get rid of the headers (the information from cell 1 to 22). That could be easily done by simple indexing (creating a sub-array using just the info from cell 23 to the end of the file).
2) I want to separate the information into different cells, using these identifiers. But I don't know how to separate them into different cells of the array.
'# item bepoch ecode label onset diff dura b_flags a_flags enable bin'
3) Do the same in step 2 to fill those columns with the data in the rest of the cells.
I'm trying to use this approach, but I'm not getting the expected results.
If someone can help me, I'd be glad.
Have you tried dragging the file into the variable workspace window and using the data import wizard? It has some nice features that normally take care of what you are trying to do automatically. Unfortunately, it seems that your text file may have unconventional spacing, but Matlab may be able to handle it if you set the delimeter to ' ' or suchlike.
I have a class with a port of dimensions [x,y] which is connected to another class having a matching port. Now I want to provide value to these variables [x,y] through external function call in which I basically read a .xml file and obtain values for x and y. But Dymola gives an error for this since during compilation it comes out as a non fixed size array.
Screenshot of error is attached.
The array sizes are structural parameters and they usually cannot depend on external function calls because they should be known at compile time. This is however supported in for example OpenModelica where a dll of the external function is built and called and the results are fetched during model compilation.
The only way to support this in all tools is to generate the model using an external tool which reads the xml and changes the .mo file with the values read.
You could probably have something like Parameters.mo:
package Parameters
constant Integer nTube = <EXTERN_NTUBE>;
constant Integer nSeg = <EXTERN_NSEG>;
end Parameters;
and your external tool will read the XML and bind and in Parameters.mo which you can then use in your models via Parameters.nTube and Parameters.nSeg. Maybe it would be good to give some defaults so that it works to use this file directly:
package Parameters
constant Integer nTube = 1;
constant Integer nSeg = 2;
end Parameters;
and then your external tool will replace 1 and 2 with the needed values before compilation.
This should be improved in Dymola 2017 (without the need for modifying the Modelica code). In earlier versions of Dymola it should work if the you translate the C-functions called to compute nTube and nSeg.
If that does not help your complete code would be needed to analyze the problem.
I want to display mat file's content to see all the results. I know that I can load it and then double click on it the content are display in the workspace, this case happen when the mat file content few information but when I have mat file content information for more than 13000 record I can't display it. could please any one help me to find any way to display mat file as table?
thanks
I do not know the format of your data (multi-dimensional, structs, cell-arrays), but there is a function called "openvar" which can be very useful for these things.
Let's define a large random 500x500x10 3d-matrix:
large = rand(500,500,10);
This variable contains 2.5 million double-values and takes up close to 20MB of memory. Opening this in the variable editor by double click in the Workspace window on "large" will usually (atleast on my system) give the following message:
"Cannot display summaries of variables with more than 524288 elements."
But you can use the "openvar"-function to open certain parts:
openvar('large(:,:,1)'); %# pass the argument as a string.
This will open the first "layer" of matrices in your Variable Editor (a 500x500 matrix in this case). This is useful if you need to look into certain parts of a large variable.
Of course you can always define new variables that contain subsets of your larger variable:
less_large = large(:,:,1);
... and then open "less_large" in the variable editor by double clicking on it in the workspace-window. But sometimes the "openvar"-method is a bit faster/easier.
You have a few options. Starting from a clear workspace, you could load the mat file into the workspace. Anything now in the workspace is in the mat file. You can use the variable viewer or parse with scripts.
If you have the Simulink toolbox, you can use Simulink.saveVars to save the contents of the workspace to a human readable m-script that would generate the same contents. It's a shame that you need Simulink to do this, as this function has nothing to do with Simulink.
How about after loading the data, and use whos to display the variables in current workspace? Note that you may want to clear all the other variables before displaying them.