# City Engine study clarifications Manual/Tutorial

Question asked by mihai_atofanei on Feb 23, 2017
Latest reply on Jun 1, 2017 by mihai_atofanei

Hy there,

My name is Mihai, I have been for the past two months getting acquainted with CE, we are  trying to implement it in our urbanism projects, and as I go deper into the reading/studying I find that I am missing some concepts along the way, that confuses me a bit, while I am trying to understands how all this works.

This being said I have a few questions that I have and an answer or a resource that could clarify these question will be appreciated:

1. Map Layers- especially the Obstacle Map layer, how are they created (I have seen the interface from CE) but my question is what type of data do you use to build a Map Layer, a practical case where it was used will be very helpful.

Ex. If you have a urbanism regulation that says your are allow to build in a specific array of heights..how would one use this info to put it in a map layer to be used when developing urban areas?

1. Atribute Sources and Display- what is the difference between Object/Shape/Layer attribute? I understand how a attribute is defined in the rule and then is displayed in the Inspector and you can change from there, but I don't understand how the 3 sources presented above are "baked" into the Inspector view

A practical example from your experience would help.

1. lowHeight= 50%: 0.4 else: 0.6

attr floorheight = rand(4, 5)

RecursiveSetbacks -->

case scope.sy > 2 * floorheight :

split(y){ 'lowHeight : Mass | ~1: Setback } else: s('1, floorheight, '1) Mass

In this case what would be the difference between the lowHeight -attribute and the floorheight attribute?

This is from Turorial 8 : Mass Modeling-http://desktop.arcgis.com/en/cityengine/latest/tutorials/tutorial-8-mass-modeling.htm

1. If you assign a rule to a shape is there a possibility to "unassign" it?

1. I have encountered the follwing terms : function/rule/command, What is the difference between them?

I will stop here for now, cheers in advance for any leads.

Mihai A.