Wrong values at screentosphere??

    Hi everyone / Klaus,
    I'm trying to get the exact (horizontal) mouse-coordinates at distortet hotspots. My assumption: A hotspot with 500px width should be displayed with a width of 45°. This is working fine. So the left and right edge of a hotspot (centered at 0°/0°) sould be -22,5° and +22,5°. But when I try to get the mouse coordinates over the left and right edge of the hotspot via screentosphere, it indicates a Position about -26° and +26°.

    I tried also to check this with the tools from tuur. The hotspot is shown perfectly in the grid, but when i hover the mouse to the left/right corner of the hotspot, mouse_ATH is again around -26°/+26°.


    The mouse_ATH (calculated via screentosphere) at the 15° grid is about 18°, at the 30° grid mouse_ATH ist around 33°.Is there anything wrong in my asumptions? Does anybody know, how to get the correct mouse coordinates?
    Thanks a lot for your help....

    I'm not sure if my understanding is right, so I made an example here:
    https://argum.video
    If I hover over the the left/right edge of the green Hotspot, the ATH-value should be -22.5°/+22.5°???
    I tried to visualize my understanding here: Could anybody tell me what is wrong in my understanding??

    The means reason is the that coordinates are simply spherical...

    In your example you have split the flat cube side image linearly into equal parts, but a spherical projection is not linear.

    E.g. a 45°fov with a 1000px base would be 414px (not 500px).
    500px would be ~53 degree fov (not 45 degree)

    E.g. here the base formals:
    px = tan(fov/2 * PI/180) * 500 * 2
    fov = 2 * arctan(px/2 / 500) * 180/PI
    (the 500 is the 1000/2 base)

    Maybe draw a circle and box around it, make a line in the middle, and the try to find the angles and lengths using trigonometry.

    Zitat von kme

    I'm not adding anything useful to the thread but this thread is not showing up anywhere when I view the forums


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