Adding a model to a background image, use light from the image

Hi, super newbie question. I’m using the perspective plotter to add a simple shape to a 2d image placed in the camera view. I have no lighting as of yet. My question is, how do I use the same background image to create the lighting around the shape (I will need to create some sun light to cast a shadow). At the moment the world lighting is effecting the background image, is there a way to avoid changing this images colour.

Thanks, Rob


3Dperspective.blend (943.4 KB)

You didn’t pack the image into the Blend File…

mm sorry, I tried to package the file I think… Included the image / file here untitled folder.zip.

I think I managed to do it to be honest. My next task is trying to match the light from the source image. So the shadow looks like the same shadow on the floor.

  1. Use Emission to keep the image bright without the effects of illumination.

  2. You want to extract the camera from the image, using fSpy. fSpy

  1. To replicate the same shadow as the image, replicate the same structure. If this is hard, synthesize it.

Create a proxy model and set as shadow catcher. Object > Visibility > Mask > Shadow Catcher. For reflections you can add the same image as environment. Merging CG with your image is done in the compositing tab.

Example file: light_setup.blend (3.3 MB)
Dragon model: https://www.renderhub.com/tredinium/dragon-asian-3d-model
Take a look at this tutorial. It is very informative: https://youtu.be/w70dMniat2M?feature=shared

hey, this is helpful. thanks for all the info. I’m pretty new to Blender. So I’ve been managing a few bits as I go. I bought The Perspective Plotter to play with the angles (still tweaking). The materials and environments are my next exploration (so to work with background images and composing 3d objects in the scene).

Hi Lucas this is great. I can’t work out how to link the dragon into the comp, but I’ll have a look (just downloaded the asset). By building the left-hand (building) part does this help the shadows and some of the reflective materials as well as the sunlight? I noticed the sky was cut out I guess this is the same image as the environment you were talking about. Really helpful. Thanks for taking time for me to explore the blender file.

Sun is coming from the left and the render engine needs something to cast shadow, so in this case just modeling the left side will suffice. Reflections are coming from World Shader where I set the same image as an environment image. In the proxy mesh, you will notice that there’s a shader to add a global illumination contribution cast from the floor to the assets and vice versa. CG is rendered separately and then composed over the image, you’ll need to learn compositing. You can also use other softwares like AE, Nuke or PS for stills. There’s a lot of information to digest but that video about shadow catcher will clarify a bit.

yeah, looking over the video is a great example of composing the 3d objects with the image. Thanks again for your help. super helpful!.

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