OSM-4D/Generic textures
This page contains description of the concept of possible generic textures for 3D city models from the page: OSM-4D. For foto textures library see [1]
Contents
Description
The real time rendering of big 3D city models with terrain model is difficult. There are use cases for which a photo texture is not necessary. For easy rendering of big areas are scheduled small textures with 64x64 Pixel. These textures have free RGB background and one of more faces einem ("doors" and "windows" representation) with other RGB value.
The textures should be used only for building facades in a lower "level of detail" LOD 1 and 2 for 3D city models.
The low resolution texture should facilitate the real-time rendering of 3D city models.
Of course, this method of representation can not show the architectural details, but it is suitable for widespread texturing of generalized city models for online - rendering.
This method of texturing is not for fotorealistic representation designed!
Textures of this type should only show number of floors of the buildings
and provide a rough orientation and recognition of the spatial situation.
Pros:
- Easily true-time rendering of 3D cities.
- Standardization of generic textures for 3D City Models
- Uniform naming system of the generic texture library: The entire texture library is small
- It allows faster texturing of large areas
Phototexturing vs. low resolution texturing
High resolution, unique textures or repeatable textures (Fototextur) look a lot better. Of course, this textures should gradually be used in all 3D buildings. But you must know about the difficulties of the high resolution texturing:
- High labor costs. For generating of unique textures each building must be photographed from each side. You get the best texture when you shot frontal photograph of each facade. These photos will then be processed (equalizing,matching).
- Expertise required. Die Fotos müssen in der Farbigkeit aneinander angepaßt werden. Autos, Bäume, Menschen, Straßenlaternen und ander störende Elemente müssen von den Bilder entfert werden. Dies ist nicht immer möglich, wenn z.B. Bäume fast die gesamte Fassade verdecken. Die Texturränder müssen wiederholbar "seamless" sein. Die Texturauflösung muß aneinander angepaßt werden.
- Naming. Bei vielen Usern und vielen Fototexturen wird schnell eine große Anzahl von großen Texturen entstehen. Entweder findet man dafür eine Lösung, die Texturen miteinander vergleicht und sortiert, oder es wird viele fast identische Texturen mit verschiedenen Namen geben. Auch gleiche Namen für verschiedene Texturen können zu Problemen führen.
- Error prone technique. Schlechte Skalierung der Texturen bzw. schlechte Platzierung passieren selbst den Profis relativ oft.
- Real-time visualization. The amount of data that will result from photo textures is relatively large. Either one is developed mechanisms that provide texture optimization, or the real-time rendering will be difficult.
Despite these difficulties, it is obviously that the future belongs to fototexturierung:
Die Modelle sehen wesentlich interessanter aus, haben einen höheren Wiedererkennungswert und beinhalten wertvolle Zusatzinformationen.
Tagging
Idea: