Atlas Path Frame Index 🔢

Here's a failure mode the atlas-camera author clearly hit and fixed: you author a 30-frame camera move, then somewhere downstream you hand-type the frame indices you need - "the last N frames of the move" and "the move's final frame" - into ImageFromBatch nodes. Then you edit the move to 5 frames, the hard-coded indices stay stale, and your "repair frame" is suddenly frame 4 of the move's beginning. Atlas Path Frame Index exists so those indices are computed from the path, never typed. It's the 🔢 in Atlas/advanced.

It's a small utility with a specific job: look at the camera path the viewport produced, and tell you the frame math that matters for the pack's in-graph two-pass fill workflow. The code is blunt about the origin story - the hand-sync "failed on first contact," which is why this node is in the pack at all.

How it works

It uses the same sampler as AtlasDisocclusionGuide (sample_camera_path), so the frame count it reports always agrees with the guide batch this node indexes into. Feed it the viewport's camera_path output and it hands back three integers plus a report:

• frame_count - how many frames the path actually has.
• last_index - the final frame's index (frame_count − 1).
• window_start - frame_count − window, clamped to 0: the first frame of your trailing window.

Those three are exactly the numbers you'd otherwise type into the ImageFromBatch nodes when you want "the last N frames of the move" and "the final frame."

Inputs and outputs

• camera_path (required) - the move, i.e. the viewport's camera_path output.
• window - trailing window length, default 5. The tooltip adds the one piece of domain knowledge you need: the WAN pass wants 4k+1 frames - so 5, 9, 13, ... Set window accordingly for a Wan 2.x video pass.

Outputs: frame_count, last_index, window_start, report.

Installing it

Core-tier, trivial:

cd <ComfyUI>/custom_nodes
git clone https://github.com/mikejamesvfx/atlas-camera.git

Restart ComfyUI. It's in Atlas/advanced - the pack's gated folder - so if it doesn't appear, set ATLAS_EXPERIMENTAL=1 before launching. ComfyUI Manager has the pack as "atlas-camera".

Common issues

If you're feeding the WAN pass, the 4k+1 rule is the one to remember - a window of 5 or 9 matches the model's expectation, anything else makes the video model unhappy at the boundary. And the whole point is that these values are live: if you edit the path after wiring this node, the indices update on the next queue. If you see a stale-looking frame being picked, check that you wired this node's outputs rather than the old hard-coded numbers - the pack's own quickstart shipped with hand-typed indices that bit people, and this node is the cure.