http://www.cgarena.com/freestuff/tutorials/maya/understanding_lights/index.html

For those of you who cannot see the embedded video player click here.

*(if my short overview of this paper is unclear, please have a look at original paper, sins i am not a mathematician, some stuff is hard to understand for me too.)

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One problem in 3-dimensional modeling for animation and film special defects is mesh topology. In order to correctly animate surfaces which undergo morphing transformations, the topology of the mesh, in other words the structure of polygons and the way they are interconnected, must be correct. This means it must follow certain rules or requirements. One of the requirements is to have a mesh which consist of quads polygons, rather then triangular polygons. This brings up another important term in 3-dimensional animation and modeling which is edge loops. This term is not scientific and used by modelers.

The edge loop is not exactly a technical term, but rather jargon used by artists. It is hard to determine what is an edge loop and what is not. The edge loop is a certain way polygons are arranged together. The idea is that the main visual or underlying structures of an object which is being modeled would be represented in a polygon arrangement. The polygons no longer define only the surface approximation of an object, but also reflect the biological or mechanical underlying structures of the represented object. When an object is animated it deforms, and in order for the object to deform realistically its structures (polygonal in this case) must represent the structures and movement which exist in real object. For example, a correct mesh topology of a human body should contain polygons which represent an approximation of the human body's volume correctly, and the way the polygons are interconnected should represent the main muscle structures. This method provides more realistic human body animation, due to the more convincing muscle movements.

When 3-dimensional objects are scanned from real life objects and usually outputted from a 3d-scanner, the mesh is irregular and does not form or represent any certain structure. The vertexes in the mesh are distributed more or less equally along the complete surface. In film or animation, such objects are usually modeled manually (Boudon 2006). The scan is used only as a reference, and the modeler has to create an object from scratch, while creating a correct mesh topology. In other words, the scanner scans only the surface without any real ability to interpret inner structures of that object. Figure 25 illustrates this.

The same problem exists with implicit surfaces, since implicit surface polygonisation topology of a mesh is quite messy and it is very hard to animate such surfaces, unless they are polygonised for each and every single frame separately (see section 2.2.4, for a short description of implicit surfaces).

Some very interesting research has been done concerning Anisotropic Polygonal remeshing, or in other words retopologisation of polygonal meshes by Alliez, Cohen-Steiner, Devillers, L'evy and Desburn. In their paper “Anisotropic Polygonal remeshing”, the authors propose a method to correct bad or irregular mesh topology (Alliez et al. 2003).

This method employs natural anisotropy meaning dependent on the direction of a given surface and tries to mimic the way an artist would create a 3 dimensional object by using the minimum number of surface elements to create a detailed surface (Alliez et al. 2003). They developed an algorithm which inputs the existing mesh, and estimates the directional fields of a given surface at each vertex. Then using the calculation of the directional fields, the algorithm estimates the minimum amount of curves necessary. Meanwhile, the algorithm creates curves which are always parallel in order to create an effective mesh topology. In the intersection of the curves, the algorithm then generates vertices. After that algorithm generates a mesh using the created vertices and direction curves as guidelines (Alliez et al. 2003).

Fig 25. Picture taken from: Pierre Alliez, David Cohen-Steiner, Olivier Devillers, Bruno Lévy, and Mathieu Desbrun 2003. Anisotropic Polygonal Remeshing. ACM SIGGRAPH 2003 Papers SIGGRAPH '03, Volume 22 Issue 3

As shown in figure 25, the overall surface shape of the model remains the same, but the number of elements dramatically decreases. Also the topology of the mesh is much better and resembles one which one would expect was created manually. This method is very valuable in 3-dimensional modeling and could potentially serve for re-meshing virtual models generated by 3-dimensional scanners or irregular mesh topologies created by implicit surface polygonisation.

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All thoughts have directional purposes, depending on how it is represented in the context matrix by how it decides to interact with the other contexts it holds a relationship with.

The true power of our thoughts comes not from the mere fraction of its existence but by how it interacts with the thoughts brought by the direction of their relationships.

Within the matrix exists a relative hierarchy of sorts.

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I made Soundpocket 1 as part of the exhibition urban interface oslo fall 2007.
From urban interface oslo blog:
"Hauntings? Dimension Doors? Time tunnels?
A boy heard what appeared to be the sound of a sheep coming from the wall of Strykejernet Art School.
A bartender at Blå was concerned when he heard running water like that from a leaking water pipe. The sound disappeared before he was able to locate it.
A seagull can be heard, but is nowhere to be seen.
Soundpocket artist HC Gilje is causing slight disturbances in the urban interfaces."

Using a directional soundbeam to project a localized sound into a public space, this sound being only heard by the people within the sound beam which can be as narrow as 50 cm in diameter. It is similar to a lightbeam, only being sound instead. When it hits a surface it is reflected.
Soundpocket 1 was installed in a narrow passageway in Oslo, connecting two parts of the city. The soundbeam was mounted on a pan/tilt head making it possible to place the sounds very precisely in the passageway.

By bouncing the sound off surfaces, it seems as if the sound is coming from a window, door, elevator, a poster on the wall or just a more general presence. This made the piece into something which added another layer of sound to the existing soundscape, blending (sometimes disappearing) into the location.
Most of the sounds would appear to belong to the site, although dislocated (like the sound of the chandelier in the wind), the sounds of birds, telephones, babies crying, dogs barking, water running etc.

It was interesting to see how the piece was received. It was obvious for me that it wouldnt work very well as a typical art piece, it has a much more interventionist nature. I wanted it to be slight distortions to the regular soundscape of the passageway, and was pleased to see that the people who used this passageway regularly were noticing these disturbances. This could be described using the first of Barthes´ three listening modes: hearing involves “evaluation of the spatio-temporal situation“ and thus, it is linked to a “notion of territory“. It places the listener on alert when new sounds which dont´t "fit in" are heard.
By adding an extra layer of sound if also made people focus on the sounds which were already there.

The inspiration from this comes from when I studied in Trondheim in the 90ies, and I heard some stories about how a directional speaker had been used to cause a certain distress on a bridge over the local river: A person walking alone across the bridge suddenly hear whispering voices. An out of tune clarinet is projected into a marching band playing on the 17th of may (Norway´s national holiday).
If these stories are true or not, doesnt really matter, it is the idea of having a private experience in a public space which intrigued me.

Soundpockets is a series of projects of intimate sound interventions in public spaces. By using fm radiowaves, soundbeams and miniature speakers to create local pockets of sound, the different projects have different scope and focus: creating private listening rooms, changing soundtracks of a location, displacement of time/or space and a bit of general disruption of everyday life.