In this video, I’ll show you the changes I made to materials, lighting, and especially post processing in Compositing in Blender 4.3, to go from the first rendering to the second one.
Video Transcript
Hello everyone! In this video, I’ll show you the changes I made to materials, lighting, and especially post processing in Compositing in Blender 4.3, to go from the first rendering to the second one. This is an analysis that might give you some ideas or suggestions you could apply to your own projects as well.
This environment is a reconstruction, based on my memories and a few photos, of a place from my childhood. That’s why there’s a map of Sicily on the left and why the map of Europe looks a bit outdated. Indeed, quite a few years have gone by. Anyway, let’s move on to the tutorial.
The scene consists only of the classroom environment, initially without any external light sources except for an HDRI image, which works well for simulating sky lighting, but not for direct sunlight. Lighting is the first of the three elements to adjust, after which we’ll move on to the materials and, most importantly, post-processing in Compositing.
What I’m showing you here is the rendering you get with the initial settings.
I introduce a Sun-type light source into the scene, orienting it so that the sunlight comes in almost horizontally, with a rotation of -80 degrees around the X axis.
I change the default color of the light source to achieve a warmer lighting effect. In my case, I lowered the Blue channel value to 0.64, but this and other values I’ll mention shouldn’t be taken as rules or general guidelines, of course.
To evaluate both the intensity and spread angle of the Sun, I temporarily set the World ambient lighting intensity to 0, so I can assess only the Sun lighting in a Rendered view.
For my rendering, I set the light intensity to 7 and changed the Angle value to 5. This particular value affects the shadows cast by the Sun light source: higher values will result in softer shadows, meaning they’ll be more diffused and blurred.
Once that’s done, I can reactivate the World lighting, which was set to 3 in my case, and start a new rendering to show you the differences. With the Sun added, we now have new shadows and a warmer overall light.
As for the Materials, I made two changes to the base PBR materials. The first change affects the walls and ceiling, where I introduced a bit of noise to make those surfaces less uniform. The second change concerns the desks and chairs, because the original wood was too matte and too light. I made it shinier and darker by adjusting the Base Color and Roughness using two separate RGB Curves nodes, as I’ll show you shortly.
Let’s start with the noise added to the walls. I multiplied a Noise Texture by the original Base Color, which darkened the surfaces in patches. I used the Factor output from the Noise Texture, which is black and white. In this texture, I set the Scale to 1 in order to get large patches, since higher values result in smaller, grainier noise.
The Factor value of the multiplication should be adjusted by checking the Preview or doing test renders until you get a satisfying result. In my case, I used a value of 0.5.
The walls and ceiling have different Materials and Textures. To use the same two new Noise and Mix nodes in the other Materials as well, I select them in the Material I just modified, then copy them to the clipboard so I can paste and connect them into the other Materials.
The teacher’s desk in the foreground already had a good color, but I lowered its Roughness, which came from a Texture, using an RGB Curves node set up like a Gamma curve, so that I wouldn’t clip the low or high values to black or white.
I used an RGB Curves node set up in the same way for the desks and chairs Material, but in this case I used it for both the Roughness and the Base Color, resulting in a darker and glossier appearance.
Before moving on to the main part of this tutorial, that is the Compositing, I’ll show you the difference between the rendering obtained by adjusting only the lighting and the one obtained by also modifying the Materials in the ways we’ve just seen.
Actually, before getting into Compositing, I also need to talk about adding some depth of field to the virtual camera. Renderings made without Depth of Field show all the objects in the scene perfectly in focus.
To preview the depth of field effect in the 3D view, I frame the scene from the virtual camera in Solid shading mode and enable the Depth of Field option in the Viewport Shading menu.
I then open the Camera object’s Object tab and enable the Depth of Field option. In this scene, there isn’t a specific object I want to keep in focus, but I do want to blur the teacher’s desk in the foreground. That’s why I selected the cabinet at the back of the classroom as the focus object.
I slightly lower the F Stop value to blur the teacher’s desk and the first row of desks, but without overdoing it. Values like 1.6 or 1.8 should work well.
Let’s finally move on to Compositing. I grouped some nodes into Frames to make the layout a bit clearer. In any case, don’t be intimidated. It’s just a few simple operations.
The first step is to slightly multiply the original render with the scene’s Ambient Occlusion to darken the areas that are more occluded. Before rendering, you’ll need to enable the Ambient Occlusion Pass in the View Layer tab of the Properties editor. I’ll show you the intermediate result with and without this step.
Next are two steps using native Compositing nodes: a slight desaturation of the render and a bit of sharpening. The desaturation is useful because sometimes Assets with PBR materials come with colors that are too saturated, making the final result look less realistic. The sharpening, done using the Filter node, helps to slightly enhance certain details, like the wood grain on the desks and chairs.
After that, I add a subtle Glare effect in Fog Glow mode. I set the Mix parameter of this node to 1, so the result is only the glow effect. I then softened and boosted this glow a bit using the Fast Gaussian Blur and RGB Curves nodes before adding it back to the sharpened render.
I increased the contrast of the render at this stage using a Brightness Contrast node, to make the image look less flat.
I then started adding optical and film effects, starting with a Lens Distortion node with a very slight distortion and the Fit option enabled, so the distorted image stays within the original frame. To set a suitable Distortion value for your renderings, pay attention to straight lines, like the corners of the walls in my scene, and curve them just slightly with a subtle barrel distortion.
I slightly multiplied the original image with a procedural Noise Texture to simulate a film grain effect. Here, you don’t want to overdo the multiplication factor, also because multiplying always slightly darkens the image.
Finally, a group of nodes implements the Vignetting effect to darken the edges of the image. There are several ways to implement this kind of effect, so there’s no need to go into the specifics of this particular node group.
All these adjustments have darkened the image, maybe a bit too much. To compensate, I'm adding a Gamma Correction node before the lens and film effects. This node allows you to brighten the image using a gamma curve, which works more gently than a simple brightness adjustment and avoids clipping the higher values. A similar result can also be achieved with the RGB Curves node by manually replicating a gamma-like curve.
That was the last change I made to the original project. Before ending the tutorial, I’ll show you the differences between the initial render and the final one, along with the intermediate steps after adjusting the lighting and the Materials.
Unlike most of my video tutorials, the PDF version of this tutorial is not currently available for download. However, you’ll find a link in the description to the page containing PDF versions of many of my other tutorials. Either way, this is a great time to subscribe to the channel and turn on notifications! That’s it for this video! I hope it was helpful! See you next time!