Surface normal is a vital concept in 3D graphics that refers to a hypothetical line parallel to a polygon’s surface. Its main purpose is to determine the reflectance of light falling on an object in a 3D scene.

## Calculating Surface Normal

Surface normal can be calculated in two ways. One is at a triangle’s vertex, where it is the average of all the adjacent vertices. Another way is to calculate it for each pixel of the triangle, as in Phong shading.

## Importance of Surface Normal

Surface normal plays a crucial role in determining the reflection of light in a 3D scene. Without it, objects in a 3D scene would appear flat and lifeless. Surface normals help to add depth and realism to 3D models, making them appear more lifelike to the viewer.

## FAQs

### What is the use of surface normal?

Surface normal is used to determine the reflectance of light falling on an object in a 3D scene. It helps to add depth and realism to 3D models.

### How is surface normal calculated?

Surface normal can be calculated at a triangle’s vertex, where it is the average of all the adjacent vertices. Another way is to calculate it for each pixel of the triangle, as in Phong shading.

## Conclusion

Surface normal is a critical concept in 3D graphics that helps to add depth and realism to 3D models. By improving the reflection of light on objects in a 3D scene, surface normals give a more lifelike appearance to the viewer.