Match Lighting in Photo Composite

Match Lighting in Photo Composite

Hi everyone!,

Does anyone have a good guide to matching the lighting in an existing photo / render when there isn't already a matching HDRI?

I'm compositing a few signs on an image backplate that was bought from iStock. We're redoing a product catalog and don't have enough real pictures that are good enough to use. I'm not sure how to go about matching the lighting in the scene though.

Thanks in advance for any advice.

This is the image I'm matching. There are actually about 19 others for me to do, all with different lighting. The majority are interiors shots. Some are real photos, but this one is a 3d render.
https://www.istockphoto.com/photo/o...nd-row-of-meeting-rooms-gm628120442-111412875

P.S. - I have the full size, non-watermarked image already. I just can't post it here.

Hi Swizl,
I don't have a good guide but if I get you right you plan to to render an object with a background camera image and need to find a way to match the lighting?

In this case I'd use Cheetah renderer with ambient occlusion, no light and a shadowmat plane beneath.

That should already work with a uniformly white environment like in the stock image you linked to.

Then you can use transparent planes (they are invisible but cast soft shadows in AO) above or beside the object to create special shadowing effects that match the situation provided by the background photo.

It gets difficult when your object has reflective parts.
Then you need a dummy HDRI that loosely matches the photo.

Thanks for the reply!

Yes, you've got it right.

I'm using the stock image as a backplate. I've already matched the perspective in Modo using the matching tool. It took some time with some help on the Modo forums to do that. This image apparently has been cropped and then a tilt-shift camera effect was applied to keep the y axis vertical.

Anyway, now that the perspective has been matched, I need to figure out the best way to light this scene. I think you are correct though, that an ambient type of light may be best. I may have to place a few strategic lights in some places. I'm going to have a ceiling mounted sign that is near the row of ceiling lights. Then there will be a wall sign and then possibly a moveable stanchion. Each photo will have a few signs comped in them. All will have Natural Satin extruded frames. So some metallic, but the finish on them has a decent amount of blur / anisotropy. I have a studio HDRI that I use for almost everything. I think that will get me most of the way there. I can rotate it until it gives me a similar light direction. I just wasn't sure if there was some method to work backwards regarding the lighting.
http://www.arrissigns.com/

Swizl said:

I just wasn't sure if there was some method to work backwards regarding the lighting.

Click to expand...

In case of a rather simple architecture like in the iStock image you could remodel the scene with a couple of scaled boxes (with full transparent material that would be invisible but cast shadows) and some area lights.

But with several different backgrounds that's too much effort.

I created a ground plane and then just called the cover command on different edges to extrude the edges into shape. Most of these I should be able to match the walls pretty easily to catch shadows. I don't need to recreated the whole interior, just enough so the signs don't look like they're floating.

I know, not helpful in any way, but looking at this one example, I don't really see that you're faster with matching the pic instead of doing it yourself anew. The chairs you could download. And rendering, well, you could do that overnight ...

With the real photos it's something else, of course. But in this case, it's not that great a picture in my humble opinion ...

Hasdrubal said:

I know, not helpful in any way, but looking at this one example, I don't really see that you're faster with matching the pic instead of doing it yourself anew. The chairs you could download. And rendering, well, you could do that overnight ...

With the real photos it's something else, of course. But in this case, it's not that great a picture in my humble opinion ...

Click to expand...

Thanks for the reply, I'll take any advice given.

I agree the image isn't the best. We had to find images that fit in certain scenarios (business setting / hospital setting / education setting) as well as showing enough wall that the signs can be seen. Sometimes the problem with some of the stock photos is that they are taken at unusual angles, or they have people blocking the wall visibility. We have a monthly subscription to iStock, which allows a certain number of downloads from their standard library. They have a higher end library of stock photos, but they are pretty expensive per image. So I was also working within those constraints. I totally would model the interiors, but unfortunately I don't have time (and probably skill) to do it properly. I can certainly model the basics, but I'm not adept at the fine details of Archviz yet, all though I am working on it!