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Adapting AEC models for GIS
3D data can come from many different sources and sometimes may not be ready for direct use in GIS.
Let's take a 3D SketchUp model of a house (3DHouse.skp by Sketchycat, see attachment: AEC2GIS.zip) downloaded from谷歌3D模型库, which we can describe as an AEC model (AEC stands for Architecture, Engineering and Construction).
For a GIS model, it contains a lot of details that do not have any meaning or value in geospatial world.For example, the model has many interior features such as walls, furniture, faucets, toilets etc.This page shows how such a model can be converted to a simpler model that has only house exterior and other features outside the house - this representation may be suitable for landscape modeling.It also includes a demo of 3D to 2D conversion.
SketchUp models often consists of multiple hierarchical levels of geometries - chairs can be aggregated with a table to make a dining set, then with all the furniture in the house;furniture can be combine with all the interiors, and then - with exterior walls, with the roof, and eventually, with everything outside - garden furniture, swimming pool, trees - and FME will read just a single feature.
Some of the geometries can have names and other attributes kept as Geometry Traits, other may stay without names and geometry traits may be very inconsistent.
At this point (this article is being written in time of early FME 2011 betas) we don't have a good tool for smart deaggregation of SketchUp files and other hierarchical models, instead, our first workspace uses several Deaggregators, GeometryNameExtractors, and Testers to get to some of the parts of the model.
After that we add TestFilter that allows separating features that have value for a GIS model from the rest:The animation below shows the model(3DGISHouse2DTrees.pdf) where all interior parts were removed.On the left side of the animation you can see a list of layers, which are common in GIS world, but did not exist in the original model:If there is a need in a more realistic landscape, FME can modify or replace some of the features.The workspace above after some modifications removes schematic 2D trees and replaces them with more realistic 3D trees and shrubs with the result you can see in3DGISHouse3DTrees.pdf:The last workspace shows how to make a simple traditional 2D map(2dHouse.pdf):
As you can see, the workspace that makes the simplest map is the most complex.红色阴影四边形显示区域,其中FME应该做的更好 - 第一,在复杂的功能解聚,然后,在转换3D功能成2D。现在我在做一个积极的,不雅的方式,这也是非常低效和不复杂的三维结构的工作 - 我崩溃,粉碎与2DForcer,GeometryCoercer,砍刀,部门间,PolygonBuilder和分散器模型。它不应该这么难 - FME肯定需要一个很好的变压器,将提取的脚印或任何2D形状沿任意裁剪平面。我希望,在目前的发展周期(或更早)结束时,我们就能这种变压器添加到FME。
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