Hair clump noise not consistent / going nuts #56075

New Issue

Acrivec Cevirca · 2018-07-21T23:35:35+02:00

Acrivec Cevirca commented

2018-07-21 23:35:35 +02:00

System Information
Windows 10, GTX980Ti, 6700k

Blender Version
Broken: 2.79.5 2018-19 02:00 51f14cfa43

Short description of error
Particle system->Hair->Children->Use Clump Noise is going nuts.
Enabling it and disabling causes completely different results each time, but the problem is that sometimes it completely changes hair look (length). See screenshots attached.

Exact steps for others to reproduce the error
On the attached .blend just keep clicking "Use clump noise", or keep it enabled and change something else, such as "use clump curve".

Clump noise disabled

Look at bear's right arm - the clump noise has been applied there in sort-of OK way. Length was changed minimally.

This one looks quite bad. But had worse.

etc.
The slightest change in hair can cause enormous inconsistency between renders. One render - bear is nicely 'trimmed', and one minute later half of the bear looks like Lady Gaga's bad hair day. The change in hair can be impossible to notice by human eye, but it affects clump noise in such random ways that render result is just unpredictable.
Changing noise size value does not help.

Bear Dusty_014_recovered.blend

**System Information** Windows 10, GTX980Ti, 6700k **Blender Version** Broken: 2.79.5 2018-19 02:00 51f14cfa43e **Short description of error** Particle system->Hair->Children->Use Clump Noise is going nuts. Enabling it and disabling causes completely different results each time, but the problem is that sometimes it completely changes hair look (length). See screenshots attached. **Exact steps for others to reproduce the error** On the attached .blend just keep clicking "Use clump noise", or keep it enabled and change something else, such as "use clump curve". ![dPF39oi- [x].png](https://archive.blender.org/developer/F4009292/dPF39oi_1_.png) Clump noise disabled ![nPD3SQW- [x].png](https://archive.blender.org/developer/F4009296/nPD3SQW_1_.png) Look at bear's right arm - the clump noise has been applied there in sort-of OK way. Length was changed minimally. ![vDnjGOq- [x].png](https://archive.blender.org/developer/F4009300/vDnjGOq_1_.png) This one looks quite bad. But had worse. etc. The slightest change in hair can cause enormous inconsistency between renders. One render - bear is nicely 'trimmed', and one minute later half of the bear looks like Lady Gaga's bad hair day. The change in hair can be impossible to notice by human eye, but it affects clump noise in such random ways that render result is just unpredictable. Changing noise size value does not help. [Bear Dusty_014_recovered.blend](https://archive.blender.org/developer/F4010778/Bear_Dusty_014_recovered.blend)

Acrivec Cevirca commented

2018-07-21 23:35:35 +02:00

Added subscriber: @Acrivec