The following are brief notes on how to use the radvis radiosity visualisation
program. Hopefully at some stage they will be replaced by highly detailed notes
with lots of demonstration images. In the meantime, if you have any questions/suggestions,
please email firstname.lastname@example.org.
This shows the current scene. The scene can be manipulated by
clicking on it with the mouse as follows:
- Left Mouse Button:
Rotate scene about its centre
- Left Mouse Button + Shift:
Zoom in and out
- Middle Mouse Button:
Translate the scene in x and y
- Middle Mouse Button + Shift:
Translate in z
- Right Mouse Button:
Pick a receiving patch. The patch will be highlighted yellow,
along with the corresponding row of the matrix.
- Right Mouse Button + Shift:
Pick an emitting patch. The patch will be highlighted green
along with the corresponding column of the matrix.
When using the right-mouse to select a patch, the initial click will select
one of the leaf nodes in the mesh. For the hierarchical meshes used in wavelet
radiosity and progressive radiosity with substructuring, elements at higher
levels in the mesh can be selected by keeping the mouse down, and dragging
away from the initial click point. The futher you drag, the higher up in the
hierarchy will the patch be selected, until eventually the root patch is
Shows the matrix corresponding to the current scene and radiosity method.
- Left Mouse Button:
Pan around the matrix
- Right Mouse Button:
Scale the matrix
These are located below the scene pane. The top line shows what the
current radiosity method is doing while it runs, and the bottom two
display various scene statistics.
The options panel contains the following three popup menus:
- Radiosity Method
- This selects the radiosity method to use. The methods are as follows:
- Matrix radiosity, with the matrix equation solved by the
successive overrelaxation technique.
- Matrix radiosity, with the matrix solved by the conjugate
- Progressive radiosity: radiosity is shot from light sources,
rather than gathered into each patch in turn.
- Progressive radiosity with a bi-level mesh. Radiosity is shot
using a relatively coarse mesh, and received over a finer one.
The receiving mesh can be subdivided in areas that have a high
radiosity gradient. (E.g., shadow boundaries.)
- Wavelet radiosity, a la Gortler et. al. In this case the mesh
is multi-level, and different types of basis functions can be
used over the mesh. If the Haar (constant) basis is used, this
reduces to Hierarchical radiosity.
- For scenes where there is no inter-reflection(!),
this will find an analytical solution to the radiosity equation.
- Selects the type of basis used for wavelet radiosity. The currently
supported bases are Haar, the flatlets F2 and F3, and the multiwavelets
M2 and M3.
- This popup menu either selects one of the built-in scenes to use, or
allows you to load an external scene file.
- Patch Subdivisions
- Controls the density of the mesh for matrix/progressive radiosity.
- For the overrelaxation method, this controls the overrelaxation amount.
(1.0 = standard gauss-seidel iteration.)
- Element Subdivisions
- Controls the density of the element mesh in the progressive +
substructuring method. For this method, Patch Subdivisions controls
the density of the mesh used for shooting radiosity, and the Element
Subdivisions setting controls the density of the mesh used for
receiving that radiosity.
- Termination Error
- The error level at which to terminate the simulation.
- Refinement Level
- For the progressive + substructuring method this determines the
threshold at which to subdivide a element of the mesh, and for
the wavelet methods, it sets a limit on the form-factor error.
(The smaller the number, the more the mesh is subdivided to
reduce this error.)
- Patch Size Limit
- Patches will not be subdivided below this limit.
- Start the radiosity simulation.
- Pause it!
- (While paused.) Perform another step of the radiosity simulation,
and then pause again.
- Prepare for another radiosity render.
- Brings up the avars window, which can be used to manipulate the
- leave the visualiser.
- Draw the scene in wireframe mode.
- Gouraud Shading
- Gouraud-shade the mesh.
- Function View
- Offset each mesh element according to how bright it
is. (Makes it easier to see the distribution of
- Patch's View
- When this is on and wavelet radiosity is selected, the scene is
displayed relative to the currently-
selected patch. Patches that contribute radiosity directly to that
patch are coloured normally; patches that contribute radiosity to its
children are drawn wireframe, and patches that contribute radiosity
to its ancestors are drawn outlined in red.
- Animate the radiosity simulation by highlighting relevant patches.
- Show Rays
- Display all rays traced for visibility determination.
- Show Links
- Show which patches are being linked together. (Wavelet radiosity
- Graded Mesh
- For the hierarchical meshes, ensure that any adjoining mesh elements
differ by at most one level in the quadtree.
- Anchored Mesh
- Use 'anchoring' to avoid problems with T-vertices, such as
discontinuities in shading. This requires that the mesh is
- Add Ambient
- Add in the ambient correction term.
- Shot Display
- Show the amount of unshot radiosity in the scene.
- BF Weighting
- Concentrates mesh refinement in those areas where significant radiosity
transfer is taking place.
- Intermixes the refinement and solution steps of the wavelet radiosity
method. If this is not selected, refinement is done first, and solution
- Plot Factors
- If a receiving and a source patch are selected, this will produce
a 3D plot of the form factor distribution over the receiving patch.
- Plot Radiosity
- Produces a 3D plot of the radiosity over the selected patch.
- Controls the number of samples used to produce the above plots.
- Dump Picture
- Saves a picture of the scene pane into the file main.tiff.
- Dump EPS
- Outputs an EPS line drawing of the current mesh.
- Dump Camera
- Outputs current camera parameters.
- Draw Matrix
- The matrix display is only drawn when this is on. When the number of
elements in the simulation gets large, displaying the matrix can take
some time, and it's often useful to turn it off temporarily.
- Adjust the camera so we see the scene from the point of view of the
- Brings up the Avars window
- Form Factors...
- Brings up the Form Factors window
This shows a list of the avars embedded in the scene, and a slider for
adjusting them. Avars can only be changed when a radiosity method
isn't running. Depending on the scene, avars can be used to vary
the emissivity or reflectivity of certain objects, or their location
- Quadrature Method
- Selects among various (somewhat obscure) variations of
form-factor calculation. 'None' uses point-to-point form factors,
'PF switch' uses the area-to-point form factor as a correction near
singularities, and the remaining options select various combinations
of area-to-point samples.
- dF Error
- Threshold dictating when to switch to the area-to-point approximation
when using the 'PF switch' method.
- The type of visibility estimation to use: no rays, one ray between
each pair of patches, sixteen from the centre of the receiver
and distributed evenly over the source, and sixteen distributed evenly
over both source and receiver.
- Vis. In Quadrature
- If this is on, visibility is sampled within the quadrature method for
higher order wavelets, rather than using the fractional visibility to
scale the results of quadrature.
- Recalc Jitter
- If this is on, a different jitter pattern is used each time
the visibility between two patches is estimated.
- Add the radiosity over the currently selected patch to this plot.
- Subtract the radiosity over the currently selected patch from this
plot. (This can be used for comparisons.)
- Dump Data...
- Save the plot data to a text file.
- Dump Image...
- Save the current picture of the plot as a TIFF file.
ajw, ph, July 15, 1997