better implicit function #channels errors

Summary: More helpful errors when the output channels aren't 1 for density and 3 for color

Reviewed By: shapovalov

Differential Revision: D40341088

fbshipit-source-id: 6074bf7fefe11c8e60fee4db2760b776419bcfee

pytorch3d/implicitron/models/metrics.py

@@ -362,6 +362,11 @@ def sample(tensor, mode):
 
 def _rgb_metrics(images, images_pred, masks, masks_pred, masks_crop):
     assert masks_crop is not None
+    if images.shape[1] != images_pred.shape[1]:
+        raise ValueError(
+            f"Network output's RGB images had {images_pred.shape[1]} "
+            f"channels. {images.shape[1]} expected."
+        )
     rgb_squared = ((images_pred - images) ** 2).mean(dim=1, keepdim=True)
     rgb_loss = utils.huber(rgb_squared, scaling=0.03)
     crop_mass = masks_crop.sum().clamp(1.0)

pytorch3d/renderer/implicit/raymarching.py

@@ -215,6 +215,7 @@ def _check_raymarcher_inputs(
     if density_1d and rays_densities.shape[-1] != 1:
         raise ValueError(
             "The size of the last dimension of rays_densities has to be one."
+            + f" Got shape {rays_densities.shape}."
         )
 
     rays_shape = rays_densities.shape[:-1]