What does "rendering a surface shaded with vertex positions" mean?

Question

I am a newbie in Computer graphics and trying to implement Dynamic Fusion following the paper. I can understand most of the paper, but there is this line bothering me "rendering the warped surface into the live frame shaded with canonical frame vertex positions using a rasterizing rendering pipeline." in section 3.3.1. It is unclear to me what "shaded with vertex positions" means because I thought you need light and camera position to do it, i.e. there is no input as "vertex position" for shading. I tried to re-read wikipedia and opengl, but I can't find the term "shaded with vertex position".

Currently I am using z-buffering to render the depth image from the surface and computing vertex and normal mapsfrom resulted depth maps for other computations. However, that line is still bugging me because clearly I don't have enough knowledge to understand it. I hope someone could help me.

Answer 1

A couple sentences later, they say:

We store this prediction as a pair of images $\{ \mathbf{v}, \mathbf{n} \} : \Omega \mapsto \mathcal{P}(\mathcal{\hat V}_c)$, where $\Omega$ is the pixel domain of the predicted images, storing the rendered canonical frame vertices and normals.

So it sounds like what they're doing is rendering the warped geometry using a fragment shader that outputs to multiple render targets (perhaps using floating-point texture formats), and stores the original vertex positions and normals to those render targets.