Maniphest T87717

Error saving emission volume in a PNG file
Closed, Duplicate
Actions

Assigned To
None
Authored By
Diogo Carvalho (sigma.17)
Apr 22 2021, 5:28 PM
Tags
  • BF Blender
Subscribers
Diogo Carvalho (sigma.17)
Philipp Oeser (lichtwerk)
Robert Guetzkow (rjg)

Description

System Information
Operating system: Windows 10
Graphics card: GTX 1650

Blender Version
Broken: blender-2.93.0-0f66dbea904f-windows64
Worked: didn't found a working version. Doesn't work in the latest 2.93b or 2.92

Short description of error
Rendering emission volume and then saving it as a PNG file with alpha channel results in a strange noisy black and white image that is different from what is displayed by the render result. I have tried other file types and this seems to be limited to PNG files. I have not tried every file types though.

Exact steps for others to reproduce the error

Volume Emission PNG Bug Report.blend1 MBDownload

Render the scene and then save the result as a png. Opening the png will show a different result from what is displayed in the render result window.

Related Objects

Event Timeline

Diogo Carvalho (sigma.17) created this task.Apr 22 2021, 5:28 PM
Robert Guetzkow (rjg) added a subscriber: Robert Guetzkow (rjg).EditedApr 22 2021, 6:11 PM

I haven't had time to look at your file, but PNG uses unassociated / straight alpha and thus cannot represent a pixel that is both simultaneously transparent and emissive. You will have to use OpenEXR for this purpose, which uses associated / premultiplied alpha. However, the issue you're seeing might be unrelated to this.

Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).May 11 2021, 5:59 PM

Although it seems generally a bad idea to use PNGs with alpha for emmisive colors, we still have T81199: Some effects [bloom, smoke, fire, ..] still don't save in PNG with transparent background (occlusion vs. emission) open for this, will merge these reports

Philipp Oeser (lichtwerk) closed this task as a duplicate of T81199: Some effects [bloom, smoke, fire, ..] still don't save in PNG with transparent background (occlusion vs. emission).May 11 2021, 5:59 PM