• Ignatius Jonathan S.

Lighting CG Objects Through Compositing

This post is dedicated for my process to create this project. Scroll down for each update.

This is the screenshot of my final node graph.

- Update 5 - April 10, 2020

After I finished with the grey ball, I decided to use other 3D models for this project. I downloaded 2 models, the BB-8 from free3d.com which was uploaded by steve1244 and the Pepsi can from turbosquid.com which is uploaded by Mihai Panait.

I animated both models and here are the pre-visualization of the animation!

Then, I rendered it by layer also AOV passes for the beauty pass. I did some color grading for the contact and the environment shadows using Nuke.

I use the same nodes from Update 4, but I changed the media. I revised the parameters in ZDefocus node so that it has the correct depth of field. Here is the first version of my final video for Project 1!

- Challenges and Mistakes -

After I rendered it and compositing it in Nuke, I saw a flicker black dots on the BB-8. It turns out that I merge the shadow over the beauty pass. Also, I wanted to convey a blue color from the reflection of the Pepsi can on the BB-8 so it would look more realistic, I guess.

- Update 4 - April 9, 2020

Using Nuke, I was able to revised the double shadow on the sphere and I also added some depth of field. Using color correct node, I adjust the shadow so it matches the environment shadow

Here is the result of the updated version!

- Update 3 - April 8, 2020

In this update, I learned how to create the shadow from the environment. Using the clean background plate and viewing from the key light, I was able to recreate the pattern of the shadow using Photoshop and Nuke.

The result of looking at the clean plate from the key light.

After that, I brought the image to Photoshop and color the shadow red so it makes me easier when creating the alpha. I used the image result for a new texture and I applied it to the sphere so that I can use it to create a mask for the shadow in Nuke.

Then, I create an simple rolling animation for the ball and this is the result

- Challenges and Mistakes -

I think the shadow on the sphere is weird and appears to be incorrect. If it is incorrect, I will definitely find what's wrong with it and fix it. Also, I already rendered out the AOV passes for the beauty pass but I still have not found out how to deal with the double shadow on the sphere.

- Update 2 - April 3, 2020

In this update, I created an HDR image using Adobe Photoshop and used it to give my scene in Maya the first light source. I also created a spotlight for the key light. I learned about render layers and how to put them together in Nuke.

This is the image that I use for the 'World Dome' in my Maya scene. Using this image and new key light to match the sun, I have the light source for my scene. Then, I created a CG sphere to match the reference photo.

Since Sarah already has the HDR image for this template, I only need to adjust more on the spot light so it matches the shadow with the reference. For the render layers: beauty, shadow , and occlusion layer, I used different shaders for the ground plane for each layer.

After that, I composited them in Nuke and did some color grading to the shadow so it matches the reference.

Here is the result! The left image is all CG ( Ball, Shadow, Occlusion) and the right image is the reference. I think the spotlight is a bit too bright, so maybe I can tone it down a bit in Maya.

- Challenges and Mistakes -

I decided to change my scene because it does not have an HDR that matches the scene very well. I think the new set is much better because it has it's own HDR and will definitely minimize the challenges for the next steps. I was still able to use my old scene, but I need to update the camera settings, camera placement, image plane and also the intensity of the light source.

- Update 1 - March 31, 2020

For this project, I'm going to integrate a CG object into a real-life background plate. I think the biggest challenge for me is to create a CG shadow that will be projected to my chosen CG objects. I know that learning new stuff through virtual classes is tough, but I was hoping that this could be an exciting challenge for me.

Chosen background plate

This background plate is from my professor's resource library. I would love to shot the plate and create a light integration kit by myself, but because of the current circumstances, I won't be able to do that. This plate was shot by Sarah. I chose this image because of the clear distinct shadow pattern that the fence created and I think it will be a challenge considering the viewer will notice right away if the shadow is not correct.

With the metadata of the background plate, I have the focal length, the resolution of the picture and what type of camera that was used. Using that information, I was able to create a CG cube and match the cube position with the reference photo. It seems like an easy job but it is not. I had a bunch of camera roll, tweaking, and dolly-ing to get a similar location and rotation with the reference cube.

I'm still brainstorming about what round CG object that I will use in this project. So, that is what I'm going to do next, choose the object.


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