So from a single primary cosmic ray, comes a shower of particles streaming towards the earth.

因此，从一条原始宇宙射线中， 会形成一连串粒子流， 流向地球。

Now let's dim the room once more and look at  a different pixel whose primary ray hits the backside of the barbershop pole.

现在让我们再次调暗房间，看看一个不同的像素，其主光线照射到理发店杆的背面。

So the next question is: how is the location where  the primary ray hits illuminated by the light sources and how bright or dark should the pixel's  color be shaded.

所以下一个问题是：主射线照射的位置如何被光源照亮，以及像素颜色应该有多亮或多暗。

These rays are called primary rays and they answer the question of what triangle and  object do the rays first hit and what basic color should be in that specific pixel.

这些光线称为主光线，它们回答了光线首先击中哪个三角形和物体以及该特定像素中的基本颜色应该是什么的问题。

This light is called indirect illumination, and in order to calculate it, we take the  intersection point from the primary ray and generate a secondary ray that bounces off it.

这种光被称为间接照明，为了计算它， 我们取主射线的交点并生成从该点反射的次级射线。

All these factors are multiplied by  the Red, Blue, and Green or RGB values of the blue stripe, which in turn changes the shading or  brightness of the pixel that the primary ray went through.

所有这些因素都乘以蓝色条纹的红色、蓝色和绿色或 RGB 值，进而改变主射线穿过的像素的阴影或亮度。

It's called path tracing because by using these  primary rays, secondary rays and shadow rays, we're finding billions of paths from the camera  through different points in the scene and to the light sources.

它被称为路径追踪，因为通过使用这些主射线、次射线和阴影射线，我们可以找到从相机穿过场景中的不同点到光源的数十亿条路径。

The purpose of bouncing the secondary rays  around and sending out shadow rays at each point is to find different paths where  light bounces off different surfaces and indirectly illuminates the original point  where the primary ray hits.

使次级射线四处反射并在每个点发出阴影射线的目的是找到光线从不同表面反射的不同路径，并间接照亮主射线击中的原始点。