ok, so long time no new posts, somthing needs to be done uppon this issue :)
ok, i guess i shuld remember the reason i have this blog. I created it in order to get some fead back from people about a topick i am interested,
which is tree generation in 3d. But it happened so that there is not even 1 post on this matter.
time to fix that. Now most of posts which will folow will be regarding the subject, and material which i will use
is based on one master thesis work. Do i have a right to use this material? i guess i do. (if not the owner of thesis shud sue me, that would be a very interesting case i think :)
so the order of posts will somewhat not folow the order of thesis, and i will get rid of chapters on 3d technik, while there is no need to write a content which is easier to find in wiki. .
Virtual tree generators have become more powerful than ever before. Traditionally tree generators are used to create trees and forests in films. Due to their professional quality these tools enable filmmakers to seamlessly blend raw footage with computer generated (CG) material. As a result the audience is not able to distinguish the difference between the two types of footage. Figure 1 shows screenshots taken from the film “Pirates of the Caribbean: Dead Man’s Chest” and shows how the natural environment has been combined with computer enhanced forests which were created by a tree generator. Current automatic tree generators are highly advanced for certain conditions but further extensions and improvements are still possible. For example commercially available tree generators such as Vue, or Xfrog can produce reasonable results when one wants to simulate a forest or a generic tree. Vue and xfrog will be discussed in more detail in Chapter 3.3.5. yet both of these tools have limitations. One of the weaknesses’ of such tools can be observed when a close up or a small detail of a tree trunk or branch is shown since the level of detail in the tree trunk, branches and roots are not always convincing when created by an automatic tree generator. This means that when a very detailed tree model is required it must be created manually instead of modeled via an application which can be very costly and time consuming.
Since many tree generation applications have already focused a lot of research on the creation of branches, and leaves this thesis is focused on research regarding tree trunks and their surface. In traditional tree generators some elements are never considered, for example usually a tree generator does not generate roots. The reason is very simple since usually the roots are under the earth so there is no need to generate them. Yet this is not necessarily true for all scenarios. In Contemporary films whether in the genre of fantasy or fiction there is a great chance that trees will appear as very complex models. This is because the more detailed the tree models are as part of the background of a scene the stronger the overall mood of the film is. For example the more intriguing and scary looking an old tree is the more it adds to the tone of the film. One way of creating this mood is to model old trees and have parts of the tree’s roots visible. The result being a more magical or mysterious characteristic to the film. The same observation could be applied to trunks. When seen in a film an interesting tree is usually very old has numerous diseases, holes, and other interesting surface elements. The branches and leaves are usually part of a large shot. One can argue this is not an attempt to create photorealism but instead to express the complexity of characteristic trees that could be found in nature.
In this thesis I will concentrate on suggesting improvements to existing tree generators. This is because current tree generators are already quite convincing in leaf generation and the structure of branching is currently very realistic. Figure 2 shows a tree generated in Vue6. Therefore the focus of my research will be on older tree trunks, which are currently generated in quite simple fashion. Commercial tree generators use bump and displacement mapping to make a trunk more realistic, but its not this is not a sufficient solution for models which require more detail. Figure 3 is a screenshot from the popular film “Pan’s Labyrinth” directed by Guillermo del Toro (2006). Figure 3 depicts old trees with complicated structures and shapes which are beyond an automatic tree generators’ capabilities.
Current tree generators are concerned with tree generation and not degradation and this is a problem since the most visually interesting trees are dying ones, sick ones or trees which are in some way or another unique.
In the next Chapter I will introduce some biological information about trees, their diseases, possible kinds of injuries and other qualities which are important factors to consider when making recommendations regarding tree generators.
In Chapter two some technical terms are presented which are very important for 3 dimensional (3D) tree creation. All of these important 3D concepts, tools and techniques relate to possible improvements to current tree generators. Chapter four consists of proposals and strategies regarding tree generation improvements. Chapter five will describe the prototype which was the result of my research into the generation tree trunk shape as part of an automatic tree generator. In Chapter six I discuss future work which could be done regarding this area of research.
Fig. 1 Picture taken from: http://www.e-onsoftware.com/ accessed may 09 2007
Fig. 2 Tree generated in Vue6.
Fig. 3 Screanshot from film “Pan’s Labyrinth” Picture taken from: http://www.panslabyrinth.com/ accessed may 09 2007
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