467 lines
13 KiB
Markdown
467 lines
13 KiB
Markdown
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<!-- cursor Session 4aeb7f9e-851f-4b2a-ae52-01c07b68e74f (2025-11-01 15:48Z) -->
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# PNG rendering error troubleshooting (2025-11-01 15:48Z)
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_**User (2025-11-01 15:48Z)**_
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why is this happening to render
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libpng error: IDAT: CRC error
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ImageInput::read_image() failed: PNG read error: IDAT: CRC error
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PNG library error
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IMB_load_image_from_memory: unknown file-format (R:\Creative\artsy\maya\2025-02 BondingArtifact\Renders\3_background\2025-10-26\3_background_dark\3_background_dark_5489.png)
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---
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_**Agent (model default, mode Agent)**_
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---
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Reviewing the open file to understand the render configuration and identify why PNGs are being corrupted.
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---
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<tool-use data-tool-type="read" data-tool-name="read_file">
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<details><summary>Tool use: **read_file** • Read file: c:\Program Files\Blender Foundation\Flamenco 3.7\scripts\TalkingHeads cycles_optix_gpu_NOBAT.js</summary>
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</details>
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</tool-use>
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---
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<tool-use data-tool-type="search" data-tool-name="codebase_search">
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<details>
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<summary>Tool use: **codebase_search** • Searched codebase "How are PNG images saved or written during rendering?" • **3** results</summary>
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| File | Lines |
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|------|-------|
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| `.gitignore` | L134 |
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| `.gitattributes` | L47 |
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| `misc/checklist.txt` | L52 |
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</details>
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</tool-use>
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---
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---
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Checking the render configuration and the corrupt file path for clues.
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---
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<tool-use data-tool-type="search" data-tool-name="codebase_search">
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<details>
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<summary>Tool use: **codebase_search** • Searched codebase "Where are render output files written or saved?" • **10** results</summary>
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| File | Lines |
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|------|-------|
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| `.gitignore` | L134 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L3573-3642 |
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| `misc/checklist.txt` | L52 |
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| `misc/metadata.bat` | L23 |
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| `misc/filenames.bat` | L1 |
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| `.cursorindexingignore` | L3 |
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| `.gitattributes` | L47 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L1475-1533 |
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| `misc/BRANDING.txt` | L2 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L1976-2034 |
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</details>
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</tool-use>
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---
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<tool-use data-tool-type="grep" data-tool-name="grep">
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<details>
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<summary>Tool use: **grep** • Grep for "3_background" • 0 matches</summary>
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Output mode: content
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_No matches found_
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</details>
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</tool-use>
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---
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---
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This PNG CRC error indicates the file was corrupted during render. The path `R:\...` suggests a network drive, which is a common source.
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Common causes:
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- Network storage issues: timeouts, interruptions, or bad connections corrupt writes
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- Concurrent access: another process (comp, preview, antivirus) reading while a worker writes
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- Incomplete writes: file read before the write finishes
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- Antivirus/backup: scanning or copying files while they’re being written
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Checking the render script for timing or synchronization issues:
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---
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<tool-use data-tool-type="read" data-tool-name="read_file">
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<details><summary>Tool use: **read_file** • Read file: c:\Program Files\Blender Foundation\Flamenco 3.7\scripts\TalkingHeads cycles_optix_gpu_NOBAT.js</summary>
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</details>
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</tool-use>
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---
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---
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## Solutions to fix this:
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### **Immediate fixes:**
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1. **Check if the file is actually corrupted**
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- Verify frame `5489` on the R: drive
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- If corrupted, re-render just that frame
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2. **Render to local storage first, then copy**
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- Change the render output to a local drive (C: or D:)
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- After rendering completes, copy to the network drive
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- Reduces corruption risk from network interruptions
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3. **Increase chunk_size**
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- In your Flamenco job settings, increase `chunk_size` (currently defaults to 1)
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- Fewer concurrent writes = less contention
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4. **Temporarily disable antivirus/backup scanning**
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- Exclude the render output folder from real-time scanning
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- Network drives are often scanned aggressively
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### **Network storage specific:**
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5. **Check network drive health**
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- Test the R: drive connection stability
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- Run `chkdsk R: /f` if it's accessible
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- Check for network timeouts or packet loss
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6. **Add file write delay/sync**
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- If possible, configure Blender to flush writes completely before finishing
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- Use `--python-expr` to add a small delay after rendering completes
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### **For the current corrupted frame:**
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The file `3_background_dark_5489.png` is corrupted. Either:
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- Re-render frame 5489 specifically, or
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- Skip it and continue (if it's not critical)
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Should I help modify the Flamenco script to render to a local directory first, or focus on diagnosing the network storage issue?
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---
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_**User (2025-11-02 23:49Z)**_
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How do I ensure my image can be denoised without rendering in future? Can saving as EXR fix it?
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---
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_**Agent (model default, mode Agent)**_
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---
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Checking how denoising and output formats are configured. Reviewing the render script for format/pass options and searching the codebase for denoising-related settings.
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---
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<tool-use data-tool-type="search" data-tool-name="codebase_search">
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<details>
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<summary>Tool use: **codebase_search** • Searched codebase "How are denoising passes or denoising data configured for rendering?" • **7** results</summary>
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| File | Lines |
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|------|-------|
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| `misc/checklist.txt` | L52 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L3573-3642 |
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| `.gitignore` | L134 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L1431-1479 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L73 |
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| `.gitattributes` | L47 |
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| `assets/Objects/gems/tx/BlackOnyx/Designer/BlackOnyx.sbs` | L1858-1925 |
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</details>
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</tool-use>
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---
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<tool-use data-tool-type="grep" data-tool-name="grep">
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<details>
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<summary>Tool use: **grep** • Grep for "denois" • 0 matches</summary>
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Output mode: content
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_No matches found_
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</details>
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</tool-use>
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---
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<tool-use data-tool-type="grep" data-tool-name="grep">
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<details>
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<summary>Tool use: **grep** • Grep for "EXR|exr|OpenEXR" • 0 matches</summary>
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Output mode: content
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_No matches found_
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</details>
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</tool-use>
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---
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---
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EXR can enable post-render denoising, but you need to enable the denoising passes when rendering.
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- EXR stores multiple passes/layers in one file (denoising data, beauty, etc.)
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- EXR stores 32-bit float data (vs 8-bit PNG), preserving detail
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- PNG cannot store denoising passes, so denoising later isn't possible
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Updating the render script to automatically enable denoising passes when EXR is selected:
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---
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<tool-use data-tool-type="read" data-tool-name="read_file">
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<details><summary>Tool use: **read_file** • Read file: c:\Program Files\Blender Foundation\Flamenco 3.7\scripts\TalkingHeads cycles_optix_gpu_NOBAT.js</summary>
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</details>
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</tool-use>
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---
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---
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Adding code to automatically enable denoising passes when rendering to EXR:
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---
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<tool-use data-tool-type="read" data-tool-name="read_file">
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<details><summary>Tool use: **read_file** • Read file: c:\Program Files\Blender Foundation\Flamenco 3.7\scripts\TalkingHeads cycles_optix_gpu_NOBAT.js</summary>
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</details>
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</tool-use>
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---
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<tool-use data-tool-type="write" data-tool-name="search_replace">
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<details><summary>Tool use: **code_edit** • Edit file: c:\Program Files\Blender Foundation\Flamenco 3.7\scripts\TalkingHeads cycles_optix_gpu_NOBAT.js</summary>
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</details>
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</tool-use>
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---
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_**User (2025-11-02 23:49Z)**_
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Don't edit anything. just tell me what I should set my render settings to.
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---
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_**Agent (model default, mode Agent)**_
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---
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Here’s what to set in Blender so you can denoise later:
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## Render settings
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### 1. Output format
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- Output Properties tab → Output section
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- Set File Format to OpenEXR or OpenEXR Multilayer
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- OpenEXR Multilayer is better if you need multiple passes later
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### 2. Enable denoising passes
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- Output Properties tab → View Layer Properties → Passes section
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- Enable:
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- Denoising Normal
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- Denoising Albedo
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- Denoising Shadow (optional, helps quality)
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### 3. Cycles denoising (during render)
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- Render Properties tab → Denoising section
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- Denoiser: OpenImageDenoise (or OptiX if on NVIDIA)
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- Enable Denoising
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- If using Passes → Data:
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- Enable Normal
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- Enable Albedo (optional if not using denoising passes)
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### 4. Render passes to save
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- View Layer Properties → Passes → Data:
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- Enable Normal
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- Enable Albedo (if you want them as separate passes)
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- With OpenEXR Multilayer, passes are stored as layers in the file
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## Why this works
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- EXR stores all passes in one file
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- 32-bit float preserves detail
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- Denoising Normal/Albedo passes let you re-denoise later
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- You can denoise post-render in Compositor or with external tools
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## After rendering
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You can re-denoise later:
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- In Blender Compositor: load the EXR, use Denoise node with the passes
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- Or keep render denoising off during render and denoise entirely in post
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Note: PNG cannot store denoising passes, so you can’t re-denoise PNG renders later. EXR is required for this workflow.
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---
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_**User (2025-11-02 23:49Z)**_
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So, when I send to sheepit, denoising will be disabled if I use the tiling option (which splits the frame into 2x2, 3x3, 4x4, or 6x6 so multiple workers can render one frame simultaneously, then they are combined) but I need to denoise it because the results are so noisy.
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---
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_**Agent (model default, mode Agent)**_
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---
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For SheepIt with tiling, you can't denoise during rendering (denoising needs the full frame), but you can denoise the combined EXR frames afterward if you save the required passes.
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## Render settings for SheepIt + tiling
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### 1. Output format
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- File Format: OpenEXR Multilayer (or OpenEXR)
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- Required so denoising passes are saved per tile and combined
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### 2. View Layer passes (critical)
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- View Layer Properties → Passes → Data:
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- Enable Denoising Normal
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- Enable Denoising Albedo
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- Enable Denoising Shadow (recommended)
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- View Layer Properties → Passes → Combined:
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- Enable Denoising Data (if available; some versions)
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### 3. Cycles render settings
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- Render Properties → Denoising:
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- Denoiser: OpenImageDenoise (or OptiX if available)
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- Keep Denoising enabled in settings
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- Note: With tiling, denoising won't run during render, but passes will still be saved.
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### 4. After SheepIt combines tiles
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You'll have EXR files with:
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- Combined beauty pass (noisy)
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- Denoising Normal pass
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- Denoising Albedo pass
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- Denoising Shadow pass (if enabled)
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## Denoise the combined frames
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### Option A: Blender Compositor
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1. Open a combined EXR in Image Editor or Compositor
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2. Use Denoise node:
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- Connect Combined (beauty)
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- Connect Denoising Normal
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- Connect Denoising Albedo
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- Optionally connect Denoising Shadow
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3. Export the denoised result
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### Option B: External tools
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- OIDN (OpenImageDenoise CLI)
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- GIMP (with EXR support)
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- Natron or other compositing software
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## Summary
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- Render EXR with Denoising Normal, Denoising Albedo (and Shadow if available)
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- Tiles will combine these passes into full-frame EXRs
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- Denoise the combined EXRs in post using those passes
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This way you get fast tiled rendering on SheepIt and clean denoised results afterward.
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---
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_**User (2025-11-03 07:09Z)**_
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Ach, looks like I can't render splits. this makes splits kind of useless for me... so I can't send this blend with such high samples because it's so long that each machine doesn't get it, but if I split it, I'll just have to denoise it after anyway... is there a better solution for denoising than the compositing solution I devised?
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---
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_**Agent (model default, mode Agent)**_
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---
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Given SheepIt’s EXR restriction (no splits), here are practical alternatives:
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## Option 1: Render with splits in PNG + enable render-time denoising
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- Render to PNG (splits allowed)
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- In Cycles: enable Denoising (OpenImageDenoise or OptiX)
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- Denoising should run per tile during render
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- Result: already denoised when tiles combine
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Note: Verify that SheepIt/Blender doesn’t disable denoising with splits. Test a single split frame first.
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## Option 2: Lower samples + better denoising (recommended)
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Modern denoisers work well with fewer samples:
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- Reduce samples (e.g., 128–256 instead of 1000+)
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- Keep denoising enabled during render
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- Render to PNG with splits enabled
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- Benefits: faster renders, workers complete tasks, denoised output
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## Option 3: AI denoisers that don’t need passes
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If render-time denoising doesn’t work with splits, use standalone denoisers:
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- Neat Video (plugin for Premiere/AE/Resolve)
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- Topaz DeNoise AI
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- Adobe Lightroom/Photoshop AI Denoise
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Trade-off: No denoising passes needed, but single-pass input only.
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## Option 4: Hybrid two-pass workflow
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If you need high samples:
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1. Pass 1: Render beauty only with splits (PNG), high samples
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2. Pass 2: Render denoising passes (Normal/Albedo) full-frame, low samples, EXR
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3. Composite: Combine passes in Blender Compositor and denoise
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Downside: Two renders, more work.
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## Recommendation
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Try Option 1 first: PNG + splits + render-time denoising enabled. If that doesn’t work or quality isn’t enough, use Option 2 (lower samples + denoising). The quality difference with modern denoisers is often minimal, and render time drops significantly.
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If you can share sample count and resolution, I can suggest specific settings.
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---
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