Questions in topic: "roof modelling" https://knowledge.亚搏在线safe.com/questions/topics/single/40245.html The latest questions for the topic "roof modelling" Compare dwg/dgn data elevation to lidar data elevation,specially roof https://knowledge.亚搏在线safe.com/questions/65080/compare-dwgdgn-data-elevation-to-lidar-data-elevat.html

Hi !

I have dwg/dng data with elevation so they are 3D polyline or polygons.Those elevation is taken by stereomapping solution.Now i want compare those elevation to airbone lidar data in same area.

Any good idea,how to do that?Buildings footprint should be quite ok,so also roof what i want compare is ok in x,y,but i think that there is some mistake by z.

 lidar 比较 海拔高度 roof modelling Thu,01 Mar 2018 15:09:51 GMT nikopetterisalo LiDAR (las) to LOD2 https://knowledge.亚搏在线safe.com/questions/58066/lidar-las-to-lod2.html

I want to create LOD2 objects from very dense LiDAR data approx 20 points/sqm.As input i only have 2D buildings as polygons,representing outer boundary of building,with no roof-ridges or other roof details.

I have tried transformers like TINGeneretor,SurfaceModeller and PointCloudSurfaceBuilder but I can't get a neat result.My main issue is going from the high resolution TIN to larger generalised planar roof surfaces.

Main question: How do I use FME to make planar areas to represent a simple roof with two (or more) roof sides?

Greatful for any ideas.

 las lidar lod2 roof modelling from points clouds Thu,16 Nov 2017 15:13:55 GMT gisase How to clip wall polygon by roof polygon and delete internal walls of buildings? https://knowledge.亚搏在线safe.com/questions/44448/how-to-clip-wall-polygon-by-roof-polygon-and-delet.html

Hi,

I want to create my own LOD2 model (based on another LOD2 model).The problem with the LOD2 I have is that the surface orientations are not correct (not outwards of buildings) and there is no logic in these errors (a solution could be determining an inner point and checking that the surface normal points away,but this does not work for building with a complex footprint).So,I have the roof polygons of the original LOD2 model as well as the minimal z-co of the building and I want to rebuild the building based on these.I labelled main volumes of buildings and extensions as separate buildings.So,one building has 1 roof shape,that consists of multiple roof polygons (often not planar).Sometimes,there are also small extensions in the roof (see picture).我的想法:

First,I use the surfacefootprintreplacer to project the roof surfaces to a horizontal plane that is at the height of the lowest roof eave.Let's say this represents the attic floor.From the attic floor,it is easy to extrude to the lowest z-co of the building (stored as an attribute).So,these walls are not the problem.

To construct the walls of the roof,I extrude the attic floor up and all of the individual roof polygons down.Then I use the clipper to determine the inside volume.This results in the correct geometry.But,now I'm stuck: there is an excess of walls in the 'attic'.I only need the walls or parts of the walls that are in contact with the outside,to get the correct building closure.I can't simply remove all vertical surfaces because some walls indeed need to be deleted as a whole,but if some part of the "wall" is in contact with the outside,then I need to keep that part of the wall (especially a problem around the small roof extensions).How do I determine this?

I hope there is some logic that I could not think of,but you could!!Already a big thanks!

Kind regards,Ina


Pictures of problem: there are 3 kinds of walls in the roof volumes:

Walls that need to be partially kept (only the part that is in contact with the outside)

Walls that need to be deleted completely (this is eg the wall under the roof edge,but is not in contact with the outside)

Walls that need to be kept completely (completely in contact with the outside)



 3d 建筑 lod2 roof modelling cut Tue,16 May 2017 15:59:28 GMT inadj Defining roof shapes without TIN / defining roof planes https://knowledge.亚搏在线safe.com/questions/40249/defining-roof-shapes-without-tin-defining-roof-pla.html

Hi,

I'm trying to work out a way to build simple 3D roof shapes for buildings that creates the minimal number of surfaces in the resulting 3D representation.My input data is a 2D set of building footprints and I have a height attribute per feature.Many of the footprint shapes are rectangular,so adding a minimally complex hipped or gable type shape on top of an extruded block of the building will likely be sufficient.My first attempt to create a roof was to use a triangulation based approach:

Input footprints -> 3DOffset (by height attribute) -> CenterLineReplacer -> TINGenerator (centre line and footprint to "breaklines" input) -> GeometryExtractor (from Triangles output).

This is OK and does create a hipped shape (see image),but the problem is I want to minimise the number of surfaces.This approach creates 6 triangles for this rectangle example - 2 end triangles,then 2 triangles for each of the long surfaces (there is no surface at the underneath the hipped shape).I think the long surfaces should be actually be 1 surface each as would be achieved my merging the (almost) planar triangles.Presumably this could be done by doing some rounding of the aspect values and then dissolving on this attribute.But that seems unnecessarily complicated.

So,can I actually create the hipped surface without a triangulation step?The Straight Skeleton of the CentreLineReplacer identifies a 2D line that looks like it be modified to create the 3D polygons directly.But how can I define the 3D planes / 3D faces?I thought maybe I could merge straight skeleton and footprint and then assign the Z values of the polygon edges that are the centre line - but what transformer would do this?

any advice much appreciated.

 3d 建筑 roof modelling hipped Mon,20 Feb 2017 16:06:57 GMT 3dmodeller