Adjust vertical perspective for 3d shape

[nic0lash]

I'd like to put a mock building into an aerial shot via a PS 3D shape. I've established the correct ground plane by using the vanishing point filter and can move the box around. However, the vertical lines don't line up correctly with the vertical lines of actual buildings, whether that's due to lens distortion or something else I'm not sure. See screenshot below, green lines line up, red ones don't.

I thought the correct approach would be to add another plane in the vanishing point filter (see 2nd screenshot below), but that seems to be ignored entirely. I guess there's really just one ground plane in the 3D space. Rotating the box doesn't really work, as that will mess up the other alignment. I guess the box would need some slight tilt/distortion if there is no further vanishing point adjustments possible. Any help greatly appreciated!

[davescm]

Hi

Matching pespective is quite difficult and requires that you match the camera angle, the camera distance and the camera lens. It can then be compounded by distortion on the original lens and whether the original image was cropped i.e offset in relation to the camera and transformed.

In some 3D apps there are plug ins to help the matching process, in Photoshop I am only aware of using vanishing point as the starter then tweaking the result manually.

Do you have any Exif data from the aerial image to indicate what lens was used?  (File >Info)

Dave

[nic0lash]

Thanks Dave, that all makes sense. The image was not further edited, but as you and Mylenium point out, the lens distortion from the drone cam is probably the culprit. Below is the info, could you point me to what I'm looking at if I want to manually correct it? And which tools/approaches I'd use?

Thing is if I'd render this out to 2D and then just use the standard transform or warp tools I can just make it fit...but I'd like to do a fair bit more of this and I would like to have measurements as realistic and accurate as possible. So I'd like to find a more sustainable approach. There's also the possibility that I take some of this into AfterEffects and even though I haven't looked into it at all yet I'd assume that would be much easier if it stays in 3D.

[davescm · Accepted solution]

Hi

You could try the Adaptive Wide Angle filter

The camera lens is shown as 4.73mm but that will be used on a small sensor so see if you can find the 35mm equivalent and set the 3D camera to use that equivalent (select the camera in the 3D panel and adjust the lens in properties)

If the image has been cropped, then you need to extend the canvas so the original centre of the photo image is back in the centre for the 3D camera. Then position your camera, groundplane and model. You can put a selection box around the section to be rendered then crop back down to the original dimensions after rendering.

Dave

[nic0lash]

Thanks Dave, I finally had enough time to look into this with the patience it required. Your suggestion is correct in that the lens  is the property to adjust. I did find the equivalent, 26mm, and there was a fair bit of interesting discussion in the drone forums around this. I also applied the wide angle lens filter, which is another useful tool I hadn't seen before...that brought it to a more reasonable base-level.

However, it still wasn't quite right and I ended up using a manual process between lens adjustment and positioning the ground plane which was a bit cumbersome initially and then became quite easy once I accepted that there's too many variables in this to make it an exact science and simply went by eye.

Really appreciate your help, thanks.

Nic

[Mylenium]

Your lens has a strong fisheye effect which would need to be removed first. Typical drone footage that PS's simple camera solver can't deal with.

Mylenium

[nic0lash]

Ok, thanks for confirming that, makes sense.