topic How to assign elevations in ArcGIS CityEngine Questions

How to assign elevations

JacquelineAlessi — Wed, 01 Jul 2015 14:15:47 GMT

I do have another question for you afterall. I have brought in a layer of all of the building floors, it contains information about the elevation of the floor of the floor and also has the height of the floor. This is very important because our buildings have irregular interstitials that have been requested to be modled true to form. I was able to create a rule to extrude each floor by the height attribute. Im stuck on trying to determine how to assign the elevations in the attributes as the "heightmap", the elevation that floor should sit on. I want this to be independant of my terrain so I assume that it has to be added to the rule. I found some information online stating that there was a way to do this but the token settings.setHeightmap say that it is undefined. Very confused: below is an example of where Im currently at:

#This attribute should be "sourced" to the object attribute

attr Height = 0

attr Elevation = 0

@StartRule

Lot -->

extrude (Height)

volume.

This is the example I atempted to use but I guess I dont understand it:

alignShapes(self, shapes, settings=None)Aligns a set of shapes. @param shapes: The set of shapes to align. @param settings: The align settings. Omit to use default settings. (default = None). @note: # align shapes of layer 'Lots' to layer 'Heightmap' lotLayer = ce.getObjectsFrom(ce.scene, ce.isLayer, ce.withName("'Lots'")) settings = AlignShapesSettings() settings.setHeightmap('Heightmap') settings.setAlignFunction(AlignShapesSettings.TRANSLATE_TO_MIN) ce.alignShapes(lotLayer, settings)

Re: How to assign elevations

Anonymous User — Wed, 01 Jul 2015 14:49:27 GMT

Hi Jacqueline,

When you bring the shape layer in, which are all individual floors of a building (or buildings?) are the shapes flat at zero elevation? And you say they have a Height and Elevation object attribute, and regardless of the terrain you want the floor at that elevation?

Chris

Re: How to assign elevations

JacquelineAlessi — Wed, 01 Jul 2015 14:59:32 GMT

Yes that is correct. I want the base of each floor to sit at the elevation specified in the Elevation attribute field. From there I will extrude them based on the Height attribute field.

Re: How to assign elevations

Anonymous User — Wed, 01 Jul 2015 15:26:39 GMT

The rule below will do it. To explain further what you are showing in you original post, the rule at the top is almost there. It just needs a t(x,y,z) which translates (moves) the model relative to its current position. There is an absolute translation, but you only want the y to be absolute, not x and z. Also, if your shapes are not coming in at elevation zero, then see the comments in the rule below, for instructions on moving them down. The code you have at the end of your post is python, which is not needed since the AlignShapesToTerrain command is available in the Shapes menu, and on the toolbar. Python can be used to work with many shapes, while CGA runs on one shape at a time.

version "2015.1"

# First, select all shapes and align them to y=0,

# using Shapes > AlignShapesToTerrain > Project All, y=0

attr Height = 0

attr Elevation = 0

@StartRule

BuildingFloorShape -->

# Move shape to elevation, relative to the current zero elevation.

t(0,Elevation,0)

# Extrude shape to make floor volume.

extrude(Height)

Re: How to assign elevations

JacquelineAlessi — Wed, 01 Jul 2015 19:40:47 GMT

Ok that worked in regards to the extrusion but the foot print is still showing at y=0 along with a shadow. How do I remove the footprint from y=0 plain? I added a screen shot of what Im talking about. I drew a pink box around one of the most obvious chunk of buildings.

Re: How to assign elevations

JacquelineAlessi — Wed, 01 Jul 2015 19:48:45 GMT

Here is another screen shot where I put in yellow the portion that I dont want to see. Can I define that in the rule as to not be shown?

Re: How to assign elevations

Anonymous User — Wed, 01 Jul 2015 20:12:36 GMT

Jacqueline,

These are settings you can change in the viewport toolbar. No rules involved. See image below for two buttons which will turn off the shapes and the shadows. The shadow control is in the gear shaped icon.

Chris

Re: How to assign elevations

JacquelineAlessi — Wed, 01 Jul 2015 20:23:30 GMT

I know how to turn the shadows off. I dont mind the shadows. Still confused about what you are saying in regards to the shapes. If I turn off the shapes in the scene window it turns off all of the shapes not just the remnants that remained at y=0. Im going to add the screen shot again wit the shadows turned off incase they are confusing you. In the picture the two ittems that you are seeing are BOTH the same shape. I cannot turn one off independantly of the other use the check box. The items in yellow are where the buildings appear prior to having the rule applied (at y=0). Once the rule is applied the items that are not in the yellow box are generated. I want to not see the items in yellow. Again turing off the shapes in the scene window doesnt work because these are the same shape. I tested using the selection tool aswell if I select one the other is automatically selected and the Scene window also only shows one item selected.

Does that make more sense?

Re: How to assign elevations

Anonymous User — Wed, 01 Jul 2015 20:55:24 GMT

Yes, you are making total sense. If I am understanding you correctly, the shapes in the yellow box are the imported shapes that you applied the rule to, and the extruded buildings that are above the yellow box are the models generated from those shapes. And yes, if you turn off their layer in the scene window, then both the shapes and their generated models will not be visible. And if you select either the shape or the model, both will be selected. You cannot turn off the original shapes from within the rule. If you want to see the models, but not the shapes, your only option is to toggle off all of the shapes using the button indicated in the image below, and you must leave the models on (4th toggle from left).

This will turn off all shapes. Please let me know if I'm confused about this.

Re: How to assign elevations

JacquelineAlessi — Thu, 02 Jul 2015 12:26:42 GMT

Ok I guess I was the one that was confused that makes more sense! Thank you.

Re: How to assign elevations

JacquelineAlessi — Thu, 02 Jul 2015 14:29:35 GMT

I have another question for you. So all above worked but I was in a sandbox scene. I brought the data into the scene that I want it to reside in and the buildings are floating above the surface of the terrain. I double checked the values for known areas and the pixels in the terrain match floor elevations within a 1/4 foot (3 inches). They are about 20-30 feet off in the scene. I know that value because I found a building with two underground levels each ~ 10 feet in height with the lowest sitting extremely close to the terrain. Any thoughts on what the issue here could be? Or how to resolve it? I also checked all the projections in ArcMap XYZ and they are identical. 😕

Re: How to assign elevations

Anonymous User — Thu, 02 Jul 2015 14:38:05 GMT

CGA rules always output meters regardless of scene units, so if your input is in feet, then use this to convert the feet input in your rules:

1 foot = 0.3048meters

so put your feet through this conversion, and use those meter values within your rule...

convertFeetToMeters(feet) = feet * 0.3048

Re: How to assign elevations

JacquelineAlessi — Thu, 02 Jul 2015 14:55:13 GMT

I was actually just about to tell you to disregard that. The group that I get the floor data from specified that they enabled the ZCoordSytem when they hadnt. I posted to quick reprojecting solved the issue.

Re: How to assign elevations

JacquelineAlessi — Mon, 06 Jul 2015 18:00:31 GMT

Hi Chris can I ask you another question about syntax?

Im trying to use the same elevation data listed above to create a rule to color the floors by elevation. I only want to use 20 shades and already calculated the correct values for each standard deviation.

The issue that I am having is with the proper syntax to combine simple float comparison operators.

For example: Works perfectly

@StartRule

BuildingByElevation -->

t(0,((Elevation)/3.28084),0)

extrude ((Height)/3.28084)

comp (f) {all:AllComponents}

AllComponents -->

case Elevation >950 : color (0,230,0)

else: PrintInfo

But how do I specify, for example, Elevation >=950 and <=1000?

I have tried all the methods that I can think of and am at a loss.

Re: How to assign elevations

Anonymous User — Mon, 06 Jul 2015 18:05:36 GMT

case Elevation >= 950 && Elevation <=1000:

If you are to make many of these in a row, make one of them have no equality as in this:

case Elevation >= 700 && Elevation <950: # this one does not catch 950

case Elevation >= 950 && Elevation <1000: # this one catches 950

Re: How to assign elevations

JacquelineAlessi — Mon, 06 Jul 2015 18:09:47 GMT

Fantastic!!!! I couldnt find it searching for my life, I tried "complex comparison operator" and a few others what would be the best way to search something like this in the future?

Re: How to assign elevations

Anonymous User — Mon, 06 Jul 2015 18:15:12 GMT

F1 for Help.

On table of contents to the left, expand CGA Shape Grammar Reference.

See "Simple Type Operations".

Re: How to assign elevations

JacquelineAlessi — Mon, 06 Jul 2015 20:10:55 GMT

So I tried to use the expression but Im not sure that it is grabbing (in the example you used) only the values 700 to 949. Everything in my model is symbolized with the highest elevations color assignment. I have 25 SD and all appear the same.

Re: How to assign elevations

JacquelineAlessi — Mon, 06 Jul 2015 20:18:09 GMT

A bit more info, I added parenthesis around the expression, the results were different but still made little sense. some floors became grey (my default if there is no value) but all of floors have values thats where I got the range of values from. the rest remained the same color as was assigned to higest elevation.

Re: How to assign elevations

JacquelineAlessi — Mon, 06 Jul 2015 20:28:28 GMT

Also the "not catch" example you gave me the "not catch 950" and the "950" all items are flagged as unexpected tokens.