Makie: Create image (as .png) of scatter projected to x-y plane?

Specific Domains Visualization
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1

Is there (I’m sure there is…) a way to produce an image (eg .png) of a Makie scatter plot projected “down” on the X-Y plane, ie like setting z to 0 and looking down from “sufficient height”. No perspective wanted. I’m projecting a pretty large scatter (coordinate x-y values up to a few hundred) and need good resolution so ballpark 8k x 4k image is what I have in mind. Scatter is pretty elongated, but I’m sure that image sizes will be adjustable.

2

Isn’t that just a 2D plot if you look from above? You can plot 3d plots into an Axis, z will just be flattened in the orthographic projection

3

In theory yes. But creating Scene, setting cam2d! on it and then scatter! does not quite seem to do what I need - the markers get too large when zooming out, bleeding into each other. Might be workable with some tweaking though.
But is there a way to create eg a high-resolution png image from this, holding the complete plot even if it is only partially on-screen (screenshot is not really an option, this need to be more automatic).

4

Can you share some sample code and/or screenshots of your plots? It’s hard to give concrete advice when we have to make guesses about your current implementation.

5

Here is a minimal working example.
After setting the camera to 2D I get a projected spiral on the x-y plane, but
zooming out the points expand in size essentially “pixelating” the projected pointcloud.
What I would need is a way to project a point cloud with markers in the size of a couple of
cm, covering a distance of say 500m and capturing an image of the entire projection with
each point roughly a pixel in size.

s = Scene()
function mwe(s::Scene)
    cam3d!(s)
    points = [Point3f(t*cos(t), t*sin(t), t) for t in LinRange(0, 2pi, 20)]
    colours = range(0, 1, 20)
    scatter!(s, points, markersize=80, color=colours)
end

mwe(s)
cam2d!(s)
6

Use scatter!(...; markerspace = SceneSpace) to make the markers scale as you zoom.

7

Neat. Suddenly marker size makes more sense :wink: Thx!

What about the “to image” part - is there a way to generate an image of the projected point cloud?
Did a PoC using screenshot but that will not cut it for “real” use, would need to have more control
of precise area to include and setting(s) for the image generation (eg resolution).

8

https://makie.juliaplots.org/stable/documentation/figure_size/index.html#exporting_a_figure_with_physical_dimensions

9

Surprised I did not see this, it sure answers the question.
I still ended up generating the image myself as the total image size gets really big.