jacenfox / build_mitsuba_scene

Build mitsuba scene files

============== Render

Make and render mitsuba scenes. You may need to install mitsuba, and source the setpath.sh. Same as python.

Coordinates:

Blender:
^z    ^	y  
|    /  
|  /  
|/  
-----------> x  
Unity(Left handed):
^y    ^	z
|    /
|  / 	
|/
-----------> -x
Mitsuba(Right handed):
^y    ^	z
|    /
|  / 	
|/
-----------> -x

Our envmap input should be:

zenith    zenith    zenith  
|-----------------------|+Y 
|	-X	-Z		+X		|		west  
|	image in latlong	|+Z		west  
|		south			|		west  
|-----------------------|-Y  
Nadir		Nadir		Nadir

Mitsuba envmap coordiantes, used to warp to sphere
|-----------------------|+Y 
|	+X	+Z		-X		|
|						|-Z
|						|
|-----------------------|-Y
They may warp in different way, need to rotate emitter 

---

Usage:

1. Model scene in Blender

   • export as mitsuba scene file
   • save as scene.xml

   All the scene parameters are in scene.xml

2. Generate new mitsuba scene files:
   use the mapping and condition file:
   python makeScenes.py -i *scene*.xml -m *mapping*.txt -c *conditions*.txt -o *PATH_out_xmls*

   or directly change the parameters in scene.xml file.

   this will generate a bunch of scenes with the condition file, useful for rendering with different parameters.
   PATH_out_xmls contains the new scene .xml file for mitsuba render.

3. Render the scene:
   mitsuba *outputScene* -o ldr.png

   or use the batch render:
   python batchRender.py -i *PATH_out_xmls* -o *PATH_output_render_result*

• Or render with MitsubaRender The scene file should be adjusted before rendering. todo with the new Demo.xml For example,

	1. Integrator should be set up in the .xml
	<integrator type="volpath"> 
		<integer name="maxDepth" value="-1"/>
		<integer name="rrDepth" value="5"/>
		<boolean name="strictNormals" value="false"/>
	</integrator>
	<integrator type="direct"> 
		<integer name="shadingSamples" value="1"/>
		<boolean name="strictNormals" value="false"/>
	</integrator>
	
	2. Add an emitter node, or else, mitsuba API will create an "sky-sun" emitter
	<emitter type="spot">
	    <transform name="toWorld">
	      <lookat origin= "0, -1, 0" target="0, -2, 0"/></transform>
	<float name="samplingWeight" value="0.1"/></emitter>
	
	3. Remove envmap, if exist.

	4. The sensor, film and sampler will be overwritten

---

SAMPLE CONDITION FILE

Example:

	imageName	lightFile	variable2
	BumpySphere_HDR		/gel/usr/hdr.hdr	value	
	BumpySphere_LDR		/gel/usr/hdrTmo.hdr	value
	%BumpySphere_AkyuzEO	AkyuzEO.hdr	value

• Notes
  • each row corresponds a new scene
  • first row are variables, see also mapping file
  • imageName is name of the new scene .xml file, also the rendered image
  • first column is always imageName, other cols are the variables in mapping file
  • seperate each column with tab not space, \t in matlab
  • use % to comment a line

---

SAMPLE MAPPING FILE

Format:
node1:node2.attribute1|attribute2|attribute3 = value1|value2|(variable_in_condition_file)
Example

	scene:sensor:film.name|type = film|ldrfilm
	scene:sensor:film:boolean.name|value = banner|false
	% tricky to hide mitsuba label
	scene:sensor:film:string.name|value = label[10,10]|'labeltag'
	scene:sensor:film:string.name|value = labeltag|label[-100,-100]

	% emitter
	scene:emitter.type = 'envmap'
	% require sensor looks at +z, south
	scene:emitter:transform:matrix.value = 1 0 0 0, 0 1 0 0, 0 0 1 0, 0 0 0 1
	scene:emitter:transform:rotate.angle|y = 0|1
	% rotate, flip, the envmap
	% prefer without rotation
	%	scene:emitter:transform:matrix.value = -1 0 0 0, 0 1 0 0, 0 0 -1 0, 0 0 0 1
	%	scene:emitter:transform:rotate.angle|y = 0|1
	
		scene:emitter:string.name|value = filename|(lightFile)

• Notes

  • Use % to comment a line

  • Follow the order to create new nodes

    1. create parentNode
       scene:parentNode.attribute = 'parent'
    2. create childNode for the parentNode
       scene:parentNode.childNode1.attribute|value = 'child'|'abc'
       cannot create childNode before parentNode exist

  • Add an attribute with value
scene:node1:node2.attribute1 = 'value1'
scene:node1:node2.attribute1|attribute2 = 'value1'|'value2'

  • Modify attribute1 while keep other attributes
    scene:node1:node2.attribute1|attribute2 = 'value1'|'value2'
    use the first attribute on the right hand to locate the node

  • Use variable to generate multiple scenes
    scene:node1:node2.attribute1 = (variable)
    Mark the right-hand value with '(' , ')'
value of the variable should be specified in condition file