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AMD GPU + Cycles + Branched Path Tracing + Reflective Caustics = Render Tiles Bug
Confirmed, NormalPublicBUG

Description

System Information
Operating system: Windows-10-10.0.18362 64 Bits
Graphics card: Radeon RX 580 Series ATI Technologies Inc. 4.5.13586 Core Profile Context 19.12.2 26.20.15002.61

Blender Version
Broken: version: 2.81 (sub 16), branch: master, commit date: 2019-12-04 11:32, hash: rBf1aa4d18d49d
Worked: (optional)

Short description of error
AMD GPU + Cycles + Branched Path Tracing + Reflective Caustics = Render Tiles Bug

Exact steps for others to reproduce the error

  1. Have an AMD GPU
  2. Have multiple glossy / reflective objects
  3. Have an HDR environment
  4. Have Reflective Caustics On
  5. Have Branched Path Tracing On
  6. Render with Cycles Hybrid Tiled ( CPU + GPU )

*Unchecking Reflective Caustics will make error tiles disappear.

Tested on:
R9 380X - bug present
RX 480 - bug present
RX 580 - bug present
Firepro M6100 - bug present
GTX 960M - no bug
*all on Windows 10 64bit

AMD Drivers:
Adrenalin 19.10.1 to 19.12.2
Enterprise 19.Q4.1

Event Timeline

Jacques Lucke (JacquesLucke) changed the task status from Needs Triage to Confirmed.Tue, Jan 14, 11:12 AM

I can reproduce the artifacts on an AMD Radeon RX 5700 on Windows. However, the artifact pattern looks different to yours. Furthermore, when I render the image twice, I get exactly the same result. Do you get different results on different AMD GPUs?

Bastien Montagne (mont29) changed the subtype of this task from "Report" to "Bug".Tue, Jan 14, 2:56 PM

This might actually be more like known limitation (afaik, AMD OpenCL is still lagging behind…), but let’s Cycles team decide here.

Subsequent renders on the same scene/frame produces different artifact patterns. This was on an RX 480.