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I'm aiming at the accurate recreation of this shot in Blender using fSpy.

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I'm struggling to find the best place to set up the vanishing point axes. This is what I have done so far. https://prnt.sc/ubxvco

If I put that fSpy file in Blender things are close but not quite right. https://prnt.sc/ubxxmw

Should I just go with what I have and try to fudge it, or have I just picked an image that is impossible to analyse?

Glorfindel
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Harry Crosby
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  • Hello :). You're almost there. The closer Z axis isn't properly aligned (try using the white building with tiles). And you can get better precision for the Y axis by putting them farther apart (e.g. left and right curb) . – jachym michal Sep 05 '20 at 09:46
  • Hi Jachym, if i use the close building for the Z axis (https://prnt.sc/uc083q) I get this result https://prnt.sc/uc08co – Harry Crosby Sep 05 '20 at 11:23
  • it also doesnt help if i use the left and right curb https://prnt.sc/uc08co – Harry Crosby Sep 05 '20 at 12:15
  • Hey :). You're right, the photo seems to be somewhat distorted. Perhaps some photographer can explain what exactly it is. – jachym michal Sep 05 '20 at 12:34

2 Answers2

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Fspy calculates the camera placement and field of view based on perspective, by tracing lines that would be straight and parallel in the real world, but in an image they converge towards a Vanishing Point.

So try to find the lines that give you the best sense of perspective and fspy will do the rest.

In this case the vertical lines of the building would work fine (most buildings are indeed vertical), and it gets a bit trickier on the street.

The lines you are using are setting in fspy seem too short, specially the vertical ones, extend the lines so that you trace most of the building.

enter image description here

Set the horizontal lines a bit further apart so that you get a better sense of the perspective.

enter image description here

no-can-do
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susu
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  • Hello :). Just a follow up - You mentioned something about perspective corrections before, could you elaborate on that a bit? It seems to be relevant in this case, since the photo seems to be distorted in a weird way :). – jachym michal Sep 05 '20 at 18:34
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    @JachymMichal if the picture has gone through any kind of perspective correction, then fspy will not work. but in this picture that seems not to be the case. – susu Sep 05 '20 at 18:35
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This image seems to have been cropped and its principal point is not in the middle.

Luckily this is a 3-point perspective (the easiest case) so it's enough to set 3 vanishing points in fSpy and it will do its job automatically.

Take a look at my Complete fSpy tutorial, as it covers all its options: https://youtu.be/daiMOYR8GS8

bartekp
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