topic Re: My buildings extent are not exactly rectangular (static shapes) in ArcGIS CityEngine Questions

My buildings extent are not exactly rectangular (static shapes)

ThibaultThibault — Sat, 16 Aug 2014 15:11:57 GMT

Hi,

I imported some buildings extent interpreted by CE as static shapes, but they are not perfect rectangles.

So every time I attempt to use a split(x/z) or a comp(f) followed by some t(x,y,z), it is all messed up.

Example using split :

General view	CGA
	version "2014.0" @StartRule A --> extrude(6) B B --> split(x){ 0.5:P\| ~1:M\| 0.5:P} P --> color("#FF80C0") M --> color("#00FF00")

General view

CGA

version "2014.0"

@StartRule

A -->

extrude(6)

B -->

split(x){

0.5:P|

~1:M|

0.5:P}

P -->

color("#FF80C0")

M -->

color("#00FF00")

Example using comp(f) :

General view	Issues
The yellow face is the "front" face of the ground floor, translated backward.	On the left it overshoots On the right it undershoots

General view

Issues

The yellow face is the "front" face of the ground floor, translated backward.

On the left it overshoots

On the right it undershoots

I guess my problem is that all my operations are based on the scope of my model, which is rectangular, but my shape, so my model, are not.

What would be the best way to handle this ?

Thank you.

Thibault

Re: My buildings extent are not exactly rectangular (static shapes)

MatthiasBuehler — Sat, 16 Aug 2014 15:46:41 GMT

A -->

innerRect

Continue.

Check the CGA docs if needed.

Ok ?

Matt

Re: My buildings extent are not exactly rectangular (static shapes)

ThibaultThibault — Sat, 16 Aug 2014 16:55:56 GMT

innerRect is a solution, but I would like not to modify the extent of my buildings.

What I am trying to do is maybe not possible, but I'd like to understand how to write a code similar to:

@StartRule

A -->

extrude(5)

split(x){

'0.5:B|

'0.5:C}

and get something like :

instead of :

Thank you.

Thibault

Re: My buildings extent are not exactly rectangular (static shapes)

DevinLavigne — Sat, 16 Aug 2014 22:40:10 GMT

In your 2nd example above, what is the shape you are starting with - its a little unclear. It looks like a mirror operation could work, unless your starting from the triangle on the left.

The solution you are looking for might be tweaking the the code in what you are trying to do. I've applied all types of rules to all types of building footprints from GIS data and I can assure you probably none of them were perfectly square.

Re: My buildings extent are not exactly rectangular (static shapes)

ThibaultThibault — Sun, 17 Aug 2014 03:13:03 GMT

The second example is maybe a little confusing.

The model (in dark grey) is manually edited, from a 2d shape (extent of a building, totally not rectangular), extruded, then I manually splited each faces to simulate what I am trying to achieve trough CGA.

If you go back to the first example part two, using comp(f), it shows what I am really trying to do.

Using Matt suggestion with "innerRect" solve the over/undershoot issues (see the yellow face) :

but the building doesn't follow the extent any more. And as I have a few of these buildings next to each other, I have gaps in between :

instead of :

but here I have the under/overshoot issues (it is the first example) :

Re: My buildings extent are not exactly rectangular (static shapes)

ThibaultThibault — Sun, 17 Aug 2014 03:18:07 GMT

Here is a simplified (and incomplete but working) version of the CGA code with which I am having trouble :

version "2014.0"

attr HEIGHT = 0

attr groundFloorHeight = 4

attr floorHeight = 4

attr roofHeight = 1.5

attr groundFloorElevation = 0.20

attr corridorWidth = 2

@StartRule

Building -->

//innerRect

extrude(HEIGHT)

split(y){

groundFloorHeight:GroundFloor|

floorHeight:Floor|

roofHeight:Roof}

GroundFloor -->

split(y){

groundFloorElevation:GroundFloorElevation|

~1:GroundFloorBuilding}

GroundFloorBuilding -->

comp(f){

front:GroundFloorFacade|

left:GroundFloorBuildingLeft|

right:GroundFloorBuildingRight|

back:GroundFloorBuildingBack}

GroundFloorFacade -->

t(0,0,-corridorWidth)

color("#FFFF00")

GroundFloorBuildingLeft -->

split(x){

~1:GroundFloorBuildingSideWall|

corridorWidth:NIL}

GroundFloorBuildingRight -->

split(x){

corridorWidth:NIL|

~1:GroundFloorBuildingSideWall}

Resulting model with over/undershoot issues on the yellow face:

Re: My buildings extent are not exactly rectangular (static shapes)

DevinLavigne — Sun, 17 Aug 2014 07:20:04 GMT

I see whats happening - your Transformation command t(0,0,-corridorWidth)is shifting along the Z-axis of the shape - so straight back, but that "straight back" is not aligned with your object since - like we know - your shape isn't square.

What I have done with the code below is isolated your ground floor - then split off the corridorWidth with a NIL so its gone. The result should be what you are looking for - on the left...

/**

* File: Thibault-NEW.cga

* Created: 17 Aug 2014 07:08:00 GMT

* Author: devlavigne

version "2014.0"

attr HEIGHT = 9.5

attr groundFloorHeight = 4

attr floorHeight = 4

attr roofHeight = 1.5

attr groundFloorElevation = 0.20

attr corridorWidth = 2

@StartRule

Building-->

[extrude(groundFloorHeight) LowerMass]

UpperMass

UpperMass-->

t(0,groundFloorHeight,0)

extrude(HEIGHT-groundFloorHeight)

split(y){floorHeight:Floor | roofHeight:Roof}

LowerMass-->

split(y) {groundFloorElevation:GroundFloorElevation | GroundFloorBuilding}

GroundFloorBuilding-->

split(z) {GroundFloorFacades | corridorWidth:NIL }

GroundFloorFacades-->

comp(f){

front:GroundFloorFacade|

left:GroundFloorBuildingLeft|

right:GroundFloorBuildingRight|

back:GroundFloorBuildingBack}

GroundFloorFacade-->

color("#FFFF00")

Re: My buildings extent are not exactly rectangular (static shapes)

ThibaultThibault — Tue, 19 Aug 2014 06:44:26 GMT

Hi Devin,

Your solution works well.

Isolating the lower mass (ground floor) of the building and applying a "split(z)" before a "comp(f)" is a good workaround (instead of a "comp(f)" and a split() on each facade one after another). It avoids over/undershooting and it is much simpler.

Thank you for your help.

Thibault

Re: My buildings extent are not exactly rectangular (static shapes)

MatthiasBuehler — Tue, 19 Aug 2014 20:56:29 GMT

Good you guys found a solution !