topic Re: Position Features from GIS data in ArcGIS CityEngine Questions

Position Features from GIS data

PaulBushnell — Thu, 30 Apr 2015 21:34:24 GMT

Hi All,

We are creating a large GIS model and then we wish to use that model to inform procedures to turn the model to a 3D representation.

As part of this process we have used the Spatial ETL Tool in ArcGis to read a set of Room Layout Plans and create simple GIS features including rooms and floor outlines.

We have then used this data to create a Room by Room model and a Floor by Floor model within City Engine 2014/2015 by taking our GIS File Geodatabase and providing rules to create simple and textured buildings. This appears to work well and show potential as a route to model a complete area.

We understand how we can use CGA scripts to texture and add features to the buildings. What we not however sure how to do the following;

The CAD drawings contain the locations of features such as Windows and Doors. We can import this from the CAD drawings and load into a FileGeodatabase without too much problem. What we are not sure about how to do is to use this data within the CGA scripts to accurately position window and door features within the building structures.

Can anyone help?

Thanks,

Paul

Re: Position Features from GIS data

Anonymous User — Fri, 01 May 2015 20:57:31 GMT

The windows and doors must be closed polygons to run rules on them. If the CAD data is 3D and the windows have proper z values (y in CE) then that is good. Otherwise you can have an attribute applied per each level of windows that indicates elevation for the windows. I'd suggest having multiple floors on their own layer, so that you can lock or hide those layers when not in use, since they might all be overlapped if no z is present. You will need CE 2015 for these features, and 2015 also imports CAD layers, where 2014.1 would collapse CAD layers into one.

Re: Position Features from GIS data

PaulBushnell — Sat, 02 May 2015 12:01:01 GMT

Thanks Chris, That's a great help.

I have imported all the Cad files into a File Geodatabase. There is no problem making the windows as polygons and setting the z value. Where I am stuck is that the floor boundary is a different feature in the GIS to the window.

If I create the outside wall then the cga rule cannot interrogate (or at least I don't know how to) the window features to see if there needs to be a window inserted. If I take the approach of taking the windows as standalone entities then I will need to make the walls first and then create a hole in the already constructed wall for the window....Is that possible?

Hope this makes sense .... In the GIS FGDB in the imported Cad I have a feature for walls and a sepearate feature class for windows, If I need to think about it differently I can.

Thanks,

Paul

Re: Position Features from GIS data

Anonymous User — Mon, 04 May 2015 16:22:34 GMT

Paul,

You are correct about one shape no interrogating another. They can only check for occlusion - where shapes intersect - and that is only a true false test to see if shapes intersect or touch or are inside of another. I worked with this type of rule recently, and how they solved it was that the window shape was responsible for generating the wall under and above the window. So the wall features were not centerline based, but were a polygon with wall thickness.

Eric Wittner, You've seen this problem recently. Any advice for Paul?

Thanks,

Chris

Re: Position Features from GIS data

Anonymous User — Mon, 04 May 2015 23:04:45 GMT

Hi Chris and Paul,

Yah, that is dead on. Either you have to have 3 stacked polygons, one for the wall to bottom of window, window up, and then window to top of wall or you make a rule that creates a blended piece of geometry. In the case of Abu Dhabi's BDMS we create a rule where they included with in the polygon the distance to bottom of sill, and then the height of the window. The top was just filled in with wall.

We exposed some handles so the values could be interactively changed from the view port.

Re: Position Features from GIS data

Anonymous User — Mon, 04 May 2015 23:08:19 GMT

I should clarify, the collapsed all their overlapping geometries from the CAD down to planar polygons. Then classed them by type, and we wrote a rule that contained those types. Windows with cill height and total window height that filled in the top with wall. Doors with door height that filled in the top with wall. Interiors walls, exteriors walls, spaces, hallways, etc.

Re: Position Features from GIS data

PaulBushnell — Tue, 05 May 2015 09:03:30 GMT

Thanks. I can see how that works. It is a shame I cannot punch through but if we cannot then will need to try this approach.

It does mean I need to process all the CAD files in a different ways to get the wall and window polygons as they are just line features at the moment. That should be possible though.

Thanks for your help,

Paul

Re: Position Features from GIS data

Anonymous User — Tue, 05 May 2015 20:12:13 GMT

Yah ... some creative model builder work is in order.

Take floor layer, feature to polygon, get floor polygon.

Take floor walls, feature to polygon, then erase walls from floor

Optional: negative buffer floor by 0.25, union with walls

Gives you thin exteriors walls as seperate polys from interior walls.

Take window layer, feature to polygon, then erase windows from walls.

May have some challenges here if windows just represent panes, and fall within the wall.

Take doors layer, feature to polygon, erase from floor

Multipart to singlepart on remaining polys of floor to get rooms/hallways.

May want to poly and erase other features such as support columns, stairs, elevators, etc.

Process needs to be done floor by floor.

When done, add field height as double to all feature classes.

Calculate field height at floor z.

Feature to 3D by Attribute data to burn the Z values into the geometry.

Re: Position Features from GIS data

PaulBushnell — Wed, 06 May 2015 09:18:35 GMT

Thanks for this. I am going to busy with my current skill level. The logic

sounds good though.

I may try this with the Spatial ETL tool as we had to use this to import

the CAD rather than model builder. Will give it a go with this or model

builder with the imported features.

*Kind regards,

Paul Bushnell

Estates Works Manager

The University of York

Providence House

Heslington, York YO10 5ZF

Tel 01904 322172*

Re: Position Features from GIS data

PaulBushnell — Thu, 07 May 2015 09:06:48 GMT

Thanks Eric.

I have got stuck on something really silly though. The room boundaries were

originally Polygons and the rooms were solid blocks. I am able to create

lines around the room boundaries but what I am struggling with is

converting the room boundary lines to wall polygons with a thickness. The

feature to polygon reconstructs the whole room as a polygon which isn't

what we want.

*Kind regards,

Paul Bushnell