I have the following issue:
When I transform from one map projection to another using Cartopy, the output picture displays a quite ugly aliasing with "steps" larger than one pixel. I attach the input and output pictures as example.
Input - PlateCarree:
Output - Transformed:
Could anyone explain me why that happens? Is it possible to correct it?
Related
I've successfully calibrated my camera and I can get the dimensions of a XLD in world coordinates with ContourToWorldPlaneXld and then HeightWidthRatioXld. This returns me the measures of a contour extracted from a shape.
Now I need to convert a value inserted by the user in mm (example in mm: 0.1) and get how many pixels the measure is, for example, to draw a line.
I need the pixel value as per request. I tried looking around in the Halcon documentation but I didn't find what I was looking for.
Also I read this answer but it' not exactly what I'm looking for.
I'm using Halcon Progress 21.11.
Edit: A possible solution could be obtaining the dimensions before converting them to world plane and then do something like pixel/world but I would prefer a better method if it exists.
I have a XLD edge, like the one in red in the sample picture below.
I need to extract start/endpoint of straight lines that reppresent it. Hough lines sort of work for this, but the results are not really replicable. minor changes in the contour produce unexpected results.
How can the contours be extracted as straight lines? (blue) with start and finish coordinates?
lines shorter than a specified length should not be counted as separate line.
Contour needs to be converted to a polygon using the following function:
gen_polygons_xld (Object, Polygons, 'ramer', 25.0)
The only adjustable parameter is the alpha (25.0) which decides the approximation threshold.
I want to convert a map I have into a healpy map. I am fairly new to working with healpy so any suggestions would be appreciated.
The current map looks like this, in the format GLONxGLATxR(Kpc):
You need to use the healpy.ang2pix function, so given your coordinates you can understand which is the associated pixel.
See https://healpy.readthedocs.io/en/latest/generated/healpy.pixelfunc.ang2pix.html
As an example, see this tutorial:
https://gist.github.com/zonca/680c68c3d60697eb0cb669cf1b41c324
I have a series of straight line segments of varying thickness connected end-to-end to create meandering path. Does anyone know a way to paint this as a smooth meandering line, sort of like vectorizing it? I am using QPainter. I haven't had any success finding an appropriate function in QPainterPath.
The data looks something like this:
[(QPointF, width), (QPointF, width), (QPointF, width), ... ]
Thanks!
EDIT: Added example image
I wanted to leave it open to creative responses, but I am just looking to move from linear interpolation (QPainter::drawLine()) to spline interpolation.
If I understand your question correctly...
Don't draw a line, draw a filled polygon that encloses your line data with the right thickness. Drawback: That requires calculations on your data beforehand.
In GNU Octave you can make a picture where different colors represent different values in a matrix. You can also add a colorbar, which shows what color corresponds to what value.
Is it possible to somehow add units to the values shown in the colorbar? Instead of saying “0.36” it would say “0.36 V/nm”? I know this is possible in Matlab, but I can’t figure out how to do it in Octave. Any good workarounds?
I assume someone here will mention that I should use matplotlib instead (that usually happens). How would you accomplish the same thing with that?
The matplotlib answer (using pylab) is
imshow(random((20,20)))
colorbar(format='%.2f V/nm')
In Octave it seems that the following works (but I'm no Octave expert so maybe there's a better way):
c=colorbar();
labels = {};
for v=get(c,'ytick'), labels{end+1} = sprintf('%.2f V/nm',v); end
set(c,'yticklabel',labels);