Blurry Render ... Possible Scaling Issue?

[Yngvai]

I’m coming over to Blender from C4D, and re-learning workflows that I had there for compositing 3D objects into live footage (tracking, lighting, etc.).

This was a render I had done using C4D and Octane, using only an HDRI (captured using Insta360 cam) of the environment for lighting. I only needed to adjust the intensity of the HDRI environment to match the lighting. The yellow Bumblebee car is the model, and all the rest is the live footage of my driveway.

I’m trying to match this now with Blender for Octane. I successfully tracked footage in Blender, created a ground plane on the driveway, and I’ve brought the model in and used the same HDRI for lighting. However, the render is very blurry, particularly towards the rear of the car.

I’m thinking this is a scaling issue. When I brought the model in, I parented an empty null to it for easy positioning/scaling. I found the model was HUGE and I had to scale it way down. In fact, as you can see in the screenshot, the scale is brought down to 0.017 of original size.

I’m also pretty sure it’s a scaling issue because if I take the original blend file of just the model, and bring in the same HDRI (no tracked background footage…just HDRI for lighting), the render is not blurry.

In C4D, you can set vector constraints along an axis and put in the length as “known” and actually enter the length. For example, if I have two tracked points on my tracked footage, and I know the distance between those points is 1.5 meters, then I can give C4D a vector constraint and tell C4D the distance between those points is 1.5 meters. Then, whenever I bring in any 3d model, it’s automatically appropriately sized.

Is there a way to do the equivalent in Blender? I would think that would fix my scaling issue. Or perhaps there’s another way to fix this? I’ve tried searching the web for info on constraints in Blender but can’t find anything on this…I only find stuff about measuring distances.

[Matakani]

Apply the scale on the bumblebee. That sheen all over the car is blender trying to make it have a large object fade into the distance look.
The problem is that blender is set to 1/100th of everything else. That causes your scale issue & makes simulations awkward because sometimes settings need to be adjusted 0.0003 when people think it should be 1 to 100.

Blenders tracking allows you to add the distance between tracking points. The scaling difference above still applies.
There is nothing like those constraints - so no surprise you found nothing.
Not really much in the way of sizing apart from this…

[Yngvai]

Yeah the problem happens though when I scale Bumblebee. The original model is about 138 units long if I use the measurement tool in Blender (Blender says meters but obviously that’s just arbitrary based on the scene settings).

The ground plane in my live action tracked scene is about 7.5 units long.

Thus, the Bumblebee model is huge relative to my tracked scene and ground plane. Thus, I shrink it way down to about 0.015 size when I bring it in and it roughly matches the size of the car in the live action scene and fits nicely on the ground plane.

But of course now the Bumblebee model is so small relative to its original size that it impacts the lighting and Blender/Octane are trying to make it look like it’s fading into the distance and giving me the blurry render.

So not sure how to fix this because resizing the model (at least resizing it using a null parented to the entire model…it’s a really complicated model with over 500 objects) itself doesn’t seem to be working.

[Yngvai]

And here’s also what I can’t figure out. If I go into the original Blender file with the model and shrink it down to 0.015 size using the empty null, and light it with the same HDRI, the render is not blurry.

So there appears to be an issue only when I bring in the scaled-down model to my tracked footage. I’m using “Append” to bring in the entire collection into the footage.

[DNorman]

@Yngvai

using “Append”

I do not think appending has to do with the problem. Are you using depth of field in the camera settings?

[Matakani]

@Matakani

Apply the scale on the bumblebee.

Ctrl-A > Apply Scale. Or Object Menu > Apply Scale.
Always keep the models scale at 1,1,1.

Using the Empty to do the scaling worked because the car is (I assume) at the correct 1,1,1.

[Yngvai]

Yes that looks to be the problem. I went into the Octane camera settings, turned off “Autofocus” under “Depth of field”, then changed the aperture to 0, and that completely removed the issue.

Thank you for the suggestion!

[Joel_RVC]

One more thing, the cameras and the viewport in blender use separate focal length properties, by default the viewport is set to 50mm and the cameras to 35mm. You could use the values ​​you used in C4d and put them in the viewport.