blender
/
blender
131
398
Fork 575
Code Issues 6.2k Pull Requests 749 Projects 19 Wiki Activity

USD: improve light units conversion #109795

Manually merged
Brecht Van Lommel merged 4 commits from brecht/blender:usd-light-units into main 2023-07-07 18:27:19 +02:00
Conversation 4 Commits 4 Files Changed 5 +86 -50
Brecht Van Lommel commented 2023-07-06 20:14:42 +02:00
Owner
Copy Link
  • Use pi factor to convert between radiant flux and intensity
  • Mark lights as normalized on export
  • Add spot light export support
  • Add treatAsPoint support for import and export
  • Empirically match normalized distant light
  • Fix wrong unnormalized point/sphere/disk light unit in Cycles

Overall it should be much closer now for all light types. Point and distant
light units are inconsistent between renderers, so not possible to match
everything there.

Ref #109404

* Use pi factor to convert between radiant flux and intensity * Mark lights as normalized on export * Add spot light export support * Add treatAsPoint support for import and export * Empirically match normalized distant light * Fix wrong unnormalized point/sphere/disk light unit in Cycles Overall it should be much closer now for all light types. Point and distant light units are inconsistent between renderers, so not possible to match everything there. Ref #109404
Brecht Van Lommel added 1 commit 2023-07-06 20:14:52 +02:00
f35d1a6278 USD: improve light units conversion 
Use pi factor to convert from radiant flux to intensity, and fix wrong
unnormalized point/sphere light unit in Cycles.

Overall it should be much closer now for all lights. But point and distant
lights are still off and seemingly without a consistent convention in other
Hydra renderers.

Ref #109404
Brecht Van Lommel requested review from Michael Kowalski 2023-07-06 20:15:27 +02:00
Brecht Van Lommel requested review from Weizhen Huang 2023-07-06 20:15:27 +02:00
Brecht Van Lommel added 1 commit 2023-07-06 21:04:00 +02:00
Brecht Van Lommel added 1 commit 2023-07-06 21:21:54 +02:00
Michael Kowalski approved these changes 2023-07-07 02:01:21 +02:00
Michael Kowalski left a comment
Member
Copy Link

@brecht The changes look consistent to me, so I'm approving this PR. Just so I understand the motivation behind this, the goal appears to be to better match Karma lighting, is that right?

@brecht The changes look consistent to me, so I'm approving this PR. Just so I understand the motivation behind this, the goal appears to be to better match Karma lighting, is that right?
Brecht Van Lommel commented 2023-07-07 09:45:22 +02:00
Author
Owner
Copy Link

I'm trying to match all Hydra renderers, but unfortunately there is no documented convention and there are inconsistencies in implementations.

  • For sphere, spot, area and disk lights, PRMan and Karma are the same and we match them. Storm can not accurately render these so difficult to compare to, but the old factor of 100 makes no sense and the new one seems okay-ish.
  • For distant lights, the PRMan unit is weird (see #109404). So I matched it to Karma. Storm doesn't support distant lights.
  • For zero radius points lights, I will have another look to see if we can do better. PRMan doesn't support them, Karma for some reason normalizes them differently than sphere lights with very small radius.
I'm trying to match all Hydra renderers, but unfortunately there is no documented convention and there are inconsistencies in implementations. * For sphere, spot, area and disk lights, PRMan and Karma are the same and we match them. Storm can not accurately render these so difficult to compare to, but the old factor of 100 makes no sense and the new one seems okay-ish. * For distant lights, the PRMan unit is weird (see #109404). So I matched it to Karma. Storm doesn't support distant lights. * For zero radius points lights, I will have another look to see if we can do better. PRMan doesn't support them, Karma for some reason normalizes them differently than sphere lights with very small radius.
👍 1
Weizhen Huang reviewed 2023-07-07 11:10:26 +02:00
source/blender/io/usd/intern/usd_writer_light.cc Outdated
@ -10,6 +10,7 @@
#include <pxr/usd/usdLux/sphereLight.h>
#include "BLI_assert.h"
#include "BLI_math_rotation.h"
Weizhen Huang commented 2023-07-07 11:10:26 +02:00
Member
Copy Link

Seems unnecessary?

Seems unnecessary?
Brecht Van Lommel commented 2023-07-07 15:03:36 +02:00
Author
Owner
Copy Link

Indeed, though after the latest changes I did need it for spot lights.

Indeed, though after the latest changes I did need it for spot lights.
brecht marked this conversation as resolved
Weizhen Huang approved these changes 2023-07-07 11:10:49 +02:00
Brecht Van Lommel added 1 commit 2023-07-07 15:00:27 +02:00
Brecht Van Lommel commented 2023-07-07 16:17:03 +02:00
Author
Owner
Copy Link

I did various fixes for zero radius point lights, they match Storm now. For Karma it's off by a factor of 4, and the same inconsistency exists in Houdini when switching Karma and Storm. So no hope of matching both and I think matching a sphere light with small radius makes most sense.

I did various fixes for zero radius point lights, they match Storm now. For Karma it's off by a factor of 4, and the same inconsistency exists in Houdini when switching Karma and Storm. So no hope of matching both and I think matching a sphere light with small radius makes most sense.
👍 1
Brecht Van Lommel manually merged commit 05c97df2de into main 2023-07-07 18:27:19 +02:00
Pablo Delgado commented 2023-07-11 15:15:54 +02:00
Contributor
Copy Link

Hello @brecht, I want to draw attention to the current ongoing effort to streamline light handling in USD/Hydra-supporting renderers over at the ASWF slack (usd-lux-discussion channel).

As part of this effort, a comparison between different renderers has been conducted, and a tighter specification is being worked out.

Hello @brecht, I want to draw attention to the current ongoing effort to streamline light handling in USD/Hydra-supporting renderers over at the ASWF slack (usd-lux-discussion channel). As part of this effort, a [comparison between different renderers](https://github.com/anderslanglands/light_comparison) has been conducted, and a tighter [specification](https://github.com/anderslanglands/light_comparison/blob/main/specification/specification.md) is being worked out.
Brecht Van Lommel commented 2023-07-11 18:10:14 +02:00
Author
Owner
Copy Link

Thanks, I will follow the discussion in usd-lux.

Thanks, I will follow the discussion in usd-lux.
Sign in to join this conversation.
Reviewers
No reviewers
Michael Kowalski
Weizhen Huang
Labels
Clear labels   
Interest
Alembic

  
Interest
Animation & Rigging

  
Interest
Asset Browser

  
Interest
Asset Browser Project Overview

  
Interest
Audio

  
Interest
Automated Testing

  
Interest
Blender Asset Bundle

  
Interest
BlendFile

  
Interest
Collada

  
Interest
Compatibility
This issue affects/is about backward or forward compatibility

  
Interest
Compositing

  
Interest
Core

  
Interest
Cycles

  
Interest
Dependency Graph

  
Interest
Development Management

  
Interest
EEVEE

  
Interest
EEVEE & Viewport

  
Interest
Freestyle

  
Interest
Geometry Nodes

  
Interest
Grease Pencil

  
Interest
ID Management

  
Interest
Images & Movies

  
Interest
Import Export

  
Interest
Line Art

  
Interest
Masking

  
Interest
Metal

  
Interest
Modeling

  
Interest
Modifiers

  
Interest
Motion Tracking

  
Interest
Nodes & Physics

  
Interest
OpenGL

  
Interest
Overlay

  
Interest
Overrides

  
Interest
Performance

  
Interest
Physics

  
Interest
Pipeline, Assets & IO

  
Interest
Platforms, Builds & Tests

  
Interest
Python API

  
Interest
Render & Cycles

  
Interest
Render Pipeline

  
Interest
Sculpt, Paint & Texture

  
Interest
Text Editor

  
Interest
Translations

  
Interest
Triaging

  
Interest
Undo

  
Interest
USD

  
Interest
User Interface

  
Interest
UV Editing

  
Interest
VFX & Video

  
Interest
Video Sequencer

  
Interest
Virtual Reality

  
Interest
Vulkan

  
Interest
Wayland
Issues relating to Wayland windowing support.

  
Interest
Workbench

  
Interest: X11

Issues relating to Xorg/X11 support.

  
Legacy
Blender 2.8 Project

  
Legacy
Milestone 1: Basic, Local Asset Browser

  
Legacy
OpenGL Error

  
Meta
Good First Issue

  
Meta
Papercut

  
Meta
Retrospective

  
Meta
Security
Issues relating to security: https://wiki.blender.org/wiki/Process/Vulnerability_Reports

  
Module
Animation & Rigging

  
Module
Core

  
Module
Development Management

  
Module
EEVEE & Viewport

  
Module
Grease Pencil

  
Module
Modeling

  
Module
Nodes & Physics

  
Module
Pipeline, Assets & IO

  
Module
Platforms, Builds & Tests

  
Module
Python API

  
Module
Render & Cycles

  
Module
Sculpt, Paint & Texture

  
Module
Triaging

  
Module
User Interface

  
Module
VFX & Video

  
Platform
FreeBSD

  
Platform
Linux

  
Platform
macOS

  
Platform
Windows

  
Priority
High

  
Priority
Low

  
Priority
Normal

  
Priority
Unbreak Now!

  
Status
Archived

  
Status
Confirmed

  
Status
Duplicate

  
Status
Needs Info from Developers

  
Status
Needs Information from User

  
Status
Needs Triage

  
Status
Resolved

  
Type
Bug

  
Type
Design

  
Type
Known Issue

  
Type
Patch

  
Type
Report

  
Type
To Do

No Label
Interest
Alembic
Interest
Animation & Rigging
Interest
Asset Browser
Interest
Asset Browser Project Overview
Interest
Audio
Interest
Automated Testing
Interest
Blender Asset Bundle
Interest
BlendFile
Interest
Collada
Interest
Compatibility
Interest
Compositing
Interest
Core
Interest
Cycles
Interest
Dependency Graph
Interest
Development Management
Interest
EEVEE
Interest
EEVEE & Viewport
Interest
Freestyle
Interest
Geometry Nodes
Interest
Grease Pencil
Interest
ID Management
Interest
Images & Movies
Interest
Import Export
Interest
Line Art
Interest
Masking
Interest
Metal
Interest
Modeling
Interest
Modifiers
Interest
Motion Tracking
Interest
Nodes & Physics
Interest
OpenGL
Interest
Overlay
Interest
Overrides
Interest
Performance
Interest
Physics
Interest
Pipeline, Assets & IO
Interest
Platforms, Builds & Tests
Interest
Python API
Interest
Render & Cycles
Interest
Render Pipeline
Interest
Sculpt, Paint & Texture
Interest
Text Editor
Interest
Translations
Interest
Triaging
Interest
Undo
Interest
USD
Interest
User Interface
Interest
UV Editing
Interest
VFX & Video
Interest
Video Sequencer
Interest
Virtual Reality
Interest
Vulkan
Interest
Wayland
Interest
Workbench
Interest: X11
Legacy
Blender 2.8 Project
Legacy
Milestone 1: Basic, Local Asset Browser
Legacy
OpenGL Error
Meta
Good First Issue
Meta
Papercut
Meta
Retrospective
Meta
Security
Module
Animation & Rigging
Module
Core
Module
Development Management
Module
EEVEE & Viewport
Module
Grease Pencil
Module
Modeling
Module
Nodes & Physics
Module
Pipeline, Assets & IO
Module
Platforms, Builds & Tests
Module
Python API
Module
Render & Cycles
Module
Sculpt, Paint & Texture
Module
Triaging
Module
User Interface
Module
VFX & Video
Platform
FreeBSD
Platform
Linux
Platform
macOS
Platform
Windows
Priority
High
Priority
Low
Priority
Normal
Priority
Unbreak Now!
Status
Archived
Status
Confirmed
Status
Duplicate
Status
Needs Info from Developers
Status
Needs Information from User
Status
Needs Triage
Status
Resolved
Type
Bug
Type
Design
Type
Known Issue
Type
Patch
Type
Report
Type
To Do
Milestone
Clear milestone
No items
No Milestone
Projects
Clear projects
No project
Assignees
Clear assignees
No Assignees
4 Participants
Notifications
Due Date
The due date is invalid or out of range. Please use the format 'yyyy-mm-dd'.

No due date set.

Dependencies

No dependencies set.

Reference: blender/blender#109795
No description provided.
Delete Branch "brecht/blender:usd-light-units"

Deleting a branch is permanent. Although the deleted branch may continue to exist for a short time before it actually gets removed, it CANNOT be undone in most cases. Continue?