"How can I fix grainy or spotty lighting effects in my 3D render?"

Graininess in 3D renders can be caused by a low sample count.

Increasing the sample count can improve render quality, but it may also increase render time.

Insufficient lighting can also cause grainy renders.

Adding more light sources or increasing the intensity of existing lights can help reduce graininess.

Noise in renders can be caused by high-frequency detail in the scene.

Reducing the level of detail or using a denoiser can help reduce noise.

Shadows can contribute to graininess in renders.

Adjusting shadow settings, such as the shadow softness and bias, can help improve render quality.

Biased rendering techniques prioritize speed and accuracy over physical accuracy.

They can be used to achieve high-quality renderings with reduced noise.

The type of light used can affect render quality.

Area lights, for example, can produce softer, more realistic shadows than point lights.

Light sampling is the process of calculating the color and intensity of light at each pixel in a render.

Increasing the number of light samples can improve render quality, but it may also increase render time.

Indirect lighting is the light that bounces off surfaces in a scene.

It can be calculated using techniques such as path tracing or photon mapping.

Global illumination is the distribution of light throughout a scene.

It can be calculated using techniques such as final gathering or image-based lighting.

The rendering equation is a mathematical formula used to calculate the color and intensity of light in a scene.

It takes into account direct and indirect lighting, as well as surface reflectance and transmittance.

Render engines use various algorithms to solve the rendering equation.

Some focus on speed, while others prioritize accuracy.

Physical accuracy is the degree to which a render accurately simulates real-world lighting conditions.

It is often sacrificed in favor of speed or simplicity.