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EXP-054Live

A 6M-parameter depth model makes our live 3D converter 60% faster

75fps

720p frames converted to 3D per second on one RTX 4070 with ZipDepth, up from 47 with Depth Anything V2

Robot cell: depth from Depth Anything V2 Small and from ZipDepth, light = near (ZipDepth (6M))Robot cell: depth from Depth Anything V2 Small and from ZipDepth, light = near (Depth Anything V2 (25M))
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Depth Anything V2 (25M)ZipDepth (6M)

ZipDepth (ECCV 2026, MIT) is a 6.1M-parameter depth network distilled from Depth Anything V2 Large. We swapped it into our live 2D-to-3D converter and scored it against the same true stereo. Depth takes 3 ms a frame instead of 12, at almost the same quality. In the browser it's a 12 MB download instead of 50 MB.

What we tried

  • Loaded ZipDepth's fused inference model in FP16, channels-last, replayed as a CUDA graph like our Depth Anything V2 path.
  • Checked its output direction against true depth (0.90 correlation with inverse depth), then ran it through the same stabiliser and stereo warp.
  • Exported it to a 12 MB half-precision ONNX file for the browser, run with ONNX Runtime Web on WebGPU.

What we measured

MeasureDepth Anything V2 SmallZipDepthNote
Depth per 720p frame11.8 ms3.0 ms
720p throughput46.6 fps75.2 fpsMedian of 3 runs
1080p throughput33.5 fps38.2 fpsThe stereo warp is now the slowest stage
Added latency, 720p live18.8 ms13.8 ms
Depth error vs true stereo2.14 px2.51 px
Right-eye match (PSNR)17.04 dB16.93 dB
Browser: depth per frame20 ms, 50 MB11 ms, 12 MBChromium, WebGPU, same RTX 4070

What went wrong

  • ZipDepth's export script crashed on Windows printing an arrow character; setting UTF-8 output fixed it.
  • Converting to half precision changed outputs by up to 4.7% on random input. We kept it, because the smaller download matters more in the browser.
  • With depth this cheap, the stereo warp and packing now take most of each frame, so that's the next thing to speed up.

What happens next

  • A faster stereo warp: a custom CUDA kernel in place of scatter operations.
  • Two live 720p feeds on one card.
  • Phones and laptops: measure the browser version on a mid-range phone.

Built with

  • ZipDepth base MIT
  • Depth Anything V2 Small (comparison) Apache-2.0
  • ONNX Runtime Web MIT
  • PyTorch BSD-3