Adding a Background Post-Render

I’m having a hard time getting a background into my model post-render. I don’t need help with the photoshop side, I get how to make a mask and all that. I just can figure out how to make my results look natural. Here is what I’m getting.

I think it probably has to do with maybe the camera position and/or the field of view. There may be other factors I’m not considering as well.

Here is another try:

Here is the SU file if anyone wants to have a look.

The shadows do not match. (The background looks like a gloomy, cloudy day, and really no well defined shadows can be seen in the background.)

The fire pit bench facing the camera is in shadow, and the shed wall also facing the camera is fully lighted.

Good call. I don’t know how I didn’t notice that. What do you think of this? It still seems like something is off to me, though the shadows match pretty well.

Yes, the shadows are much better!

What looks off is the planes of the foreground and background. They do not look like they’ll meet (vanish) at the horizon. (But it might be an illusion.) What if the foreground [model] was tilted up just a bit ?

Alright. Here is a render with the camera slightly higher.

I still feel like something doesn’t add up visually. Maybe I’ve just seen too many variations I’m going crazy lol. I see renders from others that look so realistic. I don’t know what I’m missing.

Yea, I think that looks better.

One factor is that the model doesn’t cast shadows on anything but itself. I can’t quite put my finger on it, but something also seems mismatched about the perspective.

It is getting better but like Steve, I think there’s a problem with the perspective. The structure looks too small compared to the trees. I think you need to lower the camera more. The blades of grass appear to be too large relative to the model, too. Shadow on the grass to the right of the structure would help, as well. Even down around the edges of the walk, something needs to happen.

Those stones around the edge of the circle look nice, though. :wink:

Yup. Definitely didn’t notice that until you pointed it out. That’s pretty obvious now.

I agree.

Am i going about this the wrong way? Should I be trying to place the image inside SU and render it that way? Or are there other ideas?

I first started with HDRi backgrounds (I’m using the free version of Twilight Render), but couldn’t get good results with that either. I’m not super picky about what the background is. I just want some lawn and sky in the background. And I want it to look convincing with respect to perspective and shadows and somewhat photo-realistic. Any advice appreciated.

Haha yes they turned out pretty good. Thank you for your help with that!

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I was thinking about that and trying to decide the right approach. It seems to me the focal length of SketchUp’s camera needs to be changed to be closer to that of the camera used to make the photograph. I think in this case that means a wider field of view. I think you also need to move the camera down a bit more. It’s too bad there isn’t something useful for setting up Match Photo in the background image.

when you say focal length, is that the same thing as the “Field of View” setting in SU?

yeah. You can enter the FOV as an angle or enter it as a focal length. 85 would give you and 85° FOV or 85mm gets you a focal length. Obviously those would be opposites on the FOV scale.

So a shorter focal length will give a wider FOV.

Ahh I did not know that. I thought you could only work in angles. I will give that a shot right now and post the results.

Having been a photographer ina former life, I find it easier to think in focal lengths.

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I changed the focal length from 31mm to 60 mm. I also scaled the background image up to hopefully improve the perspective. I still think I need to address the fact that the model isn’t casting a shadow on the background.


Perspective-wise, looking much improved! The right edge still seems to float above the grass, maybe because of no shadows there?

Thanks! I agree about the right edge. Any ideas on getting a shadow onto the background there?

The perspective is looking better but now I think you need to move the camera in. Your structure still looks tiny. It should probably obscure the bottom third or so of the nearest trees. Or the camera viewpoint should be higher and closer.

I’m not a photoshop adept, but it seems like you could add a layer transparent all except where the shadows should fall and that darkens the colors in the shadows.