adding rendered trees over a photo?

[KlausK]

It`s in LW 2015.3 for sure.

CHeers, Klaus 

[Dune]

I'm going to have a look, but I'm not that familiar with Layout, mostly use Modeler.

I did try my theory, and it kind of works. Problem is that the card shifts as well if moving/rotating the camera, so ther are two fields to work until it looks okay, a bit of a fickle way. So here's a feature request: make it possible to project a photo on the preview screen. Would that be easy/feasible?

[pokoy]

Are you sure your TG camera matches the real world one? Did you match the focal length, sensor dimensions and image aspect ratio? To me it looks like your TG result has a wider lens.

[Dune]

I doubt it, indeed. Looks like the perspective in the render is 'deeper'. Photo was taken with 19mm focal length data said, but using that in TG didn't work with the base square - my main aim was to match the square field of grass with the lines in the pavement - lining up, so I eyeballed even lower, more wide angle (15º). But the distant stuff moves away of course. Not easy at all. Lens distortion may also play a role, perhaps.

[digitalguru]

Do you know the crop factor of the camera that took the photo? That will impact the field of view.  What reports in the meta data most likely won't translate to a TG camera. So if the camera has a crop factor of 1.5 and the lens is 19mm it will have an "effective" focal length of 28.5. I say "effective" as the focal length doesn't change - just the field of view (have a look at https://proedu.com/blogs/photography-fundamentals/crop-factor-explained-understanding-its-impact-in-photography?srsltid=AfmBOop5pqojaH4otw486eOZdumMMcxIrQo9NcEeMBig4NKX3jcCJp0P)

Lens distortion is also a factor, especially with such a wide angle focal length. It's common practise in VFX to undistort footage to match with CG elements then re-distort once the shot has been compostited, but that invloves shooting test grids to calculate the distortion (usually done in something like Nuke, but open source Natron can do it apparently) but if you didn't take the photo that wouldn't be an option.

A lot of this is perhaps beyond the scope of your project, but figuring out the effect of the cameras crop factor might get you closer to the right TG camera settings with more confidence.

EDIT: Assume you've done this but getting the the sensor size of the camera and setting that in the TG camera will be optimal. The default settings of 36 x24mm are for a full frame sensor which has a crop factor of 1.

[pokoy]

Yeah, digitalguru is right.
Find out the camera model and look up its technical data, then use whatever the sensor size is for TG's camera sensor size, and then you can use the focal length from the image's EXIF data in TG without any conversion (e.g. crop factor).
It's important to use the same image aspect ratio, so if the image is 3:2, you need to use the same ratio in TG. Otherwise you might end up with different camera height and vertical rotation to match it, but it will inevitably lead to problems.
Lens distortion will play some role, too, and I second digitalguru's advice to apply optical correction in PS or Lightroom. It's negligible with some lenses or situations but since you need to cover a large area of the image, it makes sense to correct for lens distortion, too.
Let me know if you need more help with this, we can get in touch over email/skype etc. Setting this up correctly shouldn't take too long.

[KlausK]

This is a quick LightWave thingie. The scene file for LW 2015.3 is attached as well.

CHeers, Klaus

[Dune]

Thanks very much for your replies, gents, very much appreciated! The metadata also said something about the camera, some Canon, I'll have to look it up. Very understandable, the article about cropfactor.
And thanks for the offer for more help on this, but I just got a mail from the client that they (suddenly) have budget problems, and would I mind letting it rest for a while   Well, it's an interesting subject, and may come up again anyway (or later), so efforts weren't wasted at all. 

I'll check out LW 15 too, Klaus, thanks!