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发表时间 : 2012-12-29 23:28:15 | 浏览 : 1546    评论 : 2
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Setting Common Options
Use the Common options tab to identify and change the following items:
Output Level Strategy and offset, if desired. Options:
Highest Level with offset
Absolute

Terrain Intersection Strategy and offset, if desired. Options:
Highest Level with offset
Absolute
Highest Level with offset versus Absolute
Projecting to Absolute level n means you project to level n and all higher LODs, regardless of how many there are. Projecting Highest Level with offset n means you project to the highest n+1 LODs. These values are clamped, for example, if you choose Absolute level 5 with a 3-level grid structure, it will only be placed on the highest. Also, if you choose Highest Level with offset of 4 on a 3-level grid structure, it will be placed at level 0 and higher (3 - 4 = -1, which would be clamped to 0).
Example 1
You have a terrain with 3 levels. You project one feature as Absolute 1 and one as Highest Level with offset 1. Both features get projected to levels 1 and 2 of the terrain (where the levels are 0, 1, and 2).

Absolute 1
Highest Level with offset 1
Level 0EmptyEmpty
Level 1CultureCulture
Level 2CultureCulture

Example 2
You want to use the same style file with a different terrain - 7 levels. Now, Absolute 1 gets projected to levels 1–6 and Relative 1 gets projected to levels 5 and 6.

Absolute 1
Highest Level with offset 1
Level 0
Empty
Empty
Level 1
Culture
Empty
Level 2
Culture
Empty
Level 3
Culture
Empty
Level 4
Culture
Empty
Level 5
Culture
Culture
Level 6
Culture
Culture
In additive, the feature is only placed on the level specified. It depends on the fact that the switching structure of the files keeps this feature in. In substitutive, it places the feature at the specified level, and all higher levels, since the lower resolution feature will get swapped out.
For point models, they can have a switching structure in the model that brings in the higher resolutions. In additive, the whole model gets placed, then the LODs of the model take effect. In substitutive, the whole model gets placed at all levels, so there can be an extra cull load to process all the models.
If you are using substitutive, the Terrain Intersection Strategy is ignored. The feature is projected against the level it is written to. This means that features move with the terrain. Additive allows you to select the Terrain Intersection Strategy level. Project Culture looks at this setting to tell how to write out features. If the features are not written out in the appropriate structure, Build Structure will not be able to structure them properly.
For the best use of additive structure, use point features, that can be placed against the highest resolution and can be placed once, then switched by their own LODs. For linears and areals, it is good to use substitutive because then they get tessellated to the level that they are one, which means fewer polygons at lower resolution, and they always follow the terrain.

最近VR访客

daxia_lin 评论于2012-12-29 23:29:14
主要是红色字体那段理解不了,前面都没问题。
daxia_lin 评论于2012-12-29 23:33:30
Terrain Intersection Strategy 这个选项有一个  项可选• Highest Level with offset
• Absolute之一,这个项的值可设整数来表示层号。请问根据上述文档如何理解Terrain Intersection Strategy 的运行机制,In additive,  In substitutive,这两个短语把我整的很迷糊

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