Transcript

00:02Welcome.

00:03Do want to learn how to...

00:04...procedural model building using the CGA shape grammar in the CityEngine?

00:09Well, then this tutorial is for you.

00:12You will write your first CGA rule file.

00:16And you will get to know the Rule Editor inside the CityEngine...

00:19...and, in the end, you will create a building that looks like this one in here.

00:24So, let's start from scratch and delete this one and create a new CGA grammar file.

00:36Now, it's already open here.

00:38So, to figure out at what rule we have to start...

00:41...you need to know the shapes envelope of this lot that we want to place the building on.

00:48So bring up the inspector and locate the ShapeSymbol here which is called "Lot."

00:52So, our first rule needs to be, "Lot."

00:57So we're going to do this...

01:00...and, with the first rule, all we do is just create a volume out of our Lot.

01:05So we do an extrude and showing you one of the nice features here of the Rule Editor...

01:10...which is, by pressing CTRL+SPACE, you get the command completion, which lists...

01:16...you all the features that there are and the parameters, so in case you're unsure...

01:21...about the naming and the parameters, you can always use this...

01:25...it's a good help to start with the shape grammar.

01:28I'm going to use the second one here.

01:31And enter a value of 11 units.

01:35I now have to assign our new rule file to the Lot.

01:42And I'm going to extrude for the first time.

01:45I am going to generate for the first time.

01:47So you see, this extruded volume here with the height of 11 units -- our first generation.

01:56Now, it's always a good idea to use attributes instead of absolute numbers in the rules.

02:02So, I'm going to add a new attribute called "Height," with a value of 11...

02:09...and replace this absolute number here with the attribute.

02:13I can generate again there won't be any difference because we have the same height.

02:17But if you look at inside the Inspector again, you see that here there's a new line...

02:23...the attribute height that we declared here is appearing here.

02:29And so it's very easy later on to change the height, for example, here in the Inspector.

02:35Okay, let's get on.

02:37We have to trigger a second rule now called "Building."

02:45And from now on I'm going to copy and paste rules so I don't have to type them.

02:49So this second rule, called "Building."

02:53We'll do a component split on this volume.

02:56So what it does is it gets from volume-to-face as we take all the side faces of our volume...

03:02...and trigger the Sidefacade rules on them.

03:05I'm going to save and generate the building again using the shortcut CTRL+G now...

03:13...and you see that now we only have the side facades.

03:15We don't care about the roof at the moment.

03:18Okay, let's head over to head over to the next rule: Sidefacade.

03:29You can see here that I again declared two new attributes...

03:32...called "groundfloor height," with the value of 4 and "floor height" with a value of 3.

03:37And the new Sidefacade rule?

03:40What does it do?

03:41It splits our facade vertically; marked by this y here into a ground floor...

03:50...and into floors.

03:51Note the asterisk mark here, which stands for a repeating split.

03:57This means that the upper floors are repeated as many times as they fit in.

04:04Note also the tilde sign here which marks that...

04:08...this floor height should only be matched approximately, so...

04:12...just make sure that the floors exactly fill the volume...

04:18...so floor height might differ a bit from the 3 meters due to the tilde character.

04:26Okay, and it's always a good thing to add some color in here just for testing purposes...

04:35...so what I do here is I added the red color on the GroundFloor so we will see... 59 00:04:42,700 --> 00:04:45,666 ...that this really is the GroundFloor as it is.

04:45And to show you how important the repeating split is, I'm going to...

04:51...make the building a bit higher now.

04:53Let's make it 21 instead of 11.

04:56Regenerate, and you see how the repeating split creates as many floors as fitting.

05:04Okay, let's change this back again.

05:07Regenerate back to normal.

05:10Okay, we go on with the floor rule.

05:23Again, a new attribute, tile width and the floor is again a split rule.

05:29This time horizontally, marked by the x.

05:32It splits every floor into a wall area, then a repeating tile area, and a wall area again.

05:41Save the rule, regenerate, and you see how our facade now has these wall areas here...

05:48...every floor has this wall area and the repeating tile elements.

05:57We will now go on and subdivide the tiles further.

06:06Again, a split in x and a split in y this time combined into one rule.

06:15What it does is just divides a single tile...

06:18...even more into wall elements and this window element here.

06:24Okay, now coming to the window rule.

06:35For this, look at have a short look here into the assets; do you see this window.obj?

06:42You can preview this in the inspector.

06:45The is a pre-modeled asset modeled outside of the CityEngine.

06:49And we want to insert this element here in our window area.

06:55So, what we need to do first is declare a new variable called, "window asset..."

07:01...which has here the path to this .obj file.

07:06And, as a second step, we're going to write a new rule called "window."

07:16And insert the window asset.

07:24And you see that this is not placed correctly...

07:28...so, what we do is, we do a small translation, minus set direction...

07:40...regenerate our building; this was too far, this looks quite good.

07:50Okay, so we already have a facade with some window elements in...

07:54...but now we want to have textures on the windows.

07:57Let's head over again to our asset folder and open the textures.

08:02See the window1.tif.

08:05See this texture we want to insert?

08:07On the windows?

08:11So again we define a new variable.

08:15Up here, called "window text," with a path to our texture.

08:20And we use the color map command to declare a texture.

08:27This one here; just before we insert the asset.

08:31Save the rule.

08:32Regenerate.

08:33And we have textures on the windows.

08:37Now the tutorials have shown how the rest of the facade texture as well.

08:41I'm going to skip this for now and just load this rule file and regenerate.

08:53And you see how their additional texture, mainly on the wall elements...

08:58...these are actually two layers of texture...

09:01...a dirt map with some dirt here on the floor and on the roof.

09:05And the brick texture on all elements.

09:11Now if you look at the polygon count here.

09:14This is quite a high polygon count coming from this complex asset here.

09:18So we're going to now create another version of this building with less detail.

09:25We're going to exchange this asset here with a normal texture plane.

09:32So I'm going to open up this Rule File here.

09:36And head over to the Window rule look at here the Outline...

09:42...that lists all the rules so you can easily jump to the Window rule.

09:47Okay, now what we do is...

09:51...we create a new attribute called "LOD," for "Level of Detail,' and declare it to 1.

09:57Now in the Window rule, you want to quickly be able to switch between the level of details.

10:02So we make a conditional rule in the window rule.

10:07So, let's say in the case in case that Level of Detail is bigger than 1, and bigger than 0...

10:15...we just use our old rule just inserting the asset.

10:35All we do is define material...

10:41...I'm going to define this texture here shortly; copied from the old rule.

10:54Here we go.

10:55So what we do is define the texture to be used here, but we don't do any...

11:00...any inserts of window assets.

11:02We need to set up the UVs because we don't have an asset yet.

11:04And "bake" it; please refer to the tutorial for details about that.

11:09Now, we have this new attribute here that we can switch here, so...

11:15...instead of using Level of Detail 1, the high resolution version is switched to 0.

11:25We regenerate the building and watch out for the windows.

11:29They're exchanged with normal planes here.

11:32You can go to the on texture mode to see this more detailed.

11:41Okay, as a last step now, we will add some random variation to our buildings.

11:48So go over to the scene, select delete this model; select some more lots here.

12:11Say, if we generate them now...

12:17...they all have the same height and are totally identical, which is not too realistic.

12:21So, we're going to bring up the rule set and change the height parameter...

12:30...to a random value going from 11 to 30, and reselect our block.

12:40Regenerate the buildings and you see how they get different heights.

12:44You can also test this on a single building by using the wand here.

12:51Every time you hit the wand, a new random seed is generated...

12:55...and the new random value for height is created.

Copyright 2014 Esri
Auto Scroll (on)Enable or disable the automatic scrolling of the transcript text when the video is playing. You can save this option if you login

Use Basic Shape Grammar in CityEngine

This video tutorial provides a guide to model buildings using the CGA shape grammar in CityEngine version 2008.2.

  • Recorded: Dec 13th, 2011
  • Runtime: 13:00
  • Views: 2254
  • Published: Dec 14th, 2011
  • Night Mode (Off)Automatically dim the web site while the video is playing. A few seconds after you start watching the video and stop moving your mouse, your screen will dim. You can auto save this option if you login.
  • HTML5 Video (Off) Play videos using HTML5 Video instead of flash. A modern web browser is required to view videos using HTML5.
Download VideoDownload this video to your computer.
<Embed>Customize the colors and use the HTML code to include this video on your own website
480x270
720x405
960x540
Custom
Width:
Height:
Start From:
Player Color:

Right-click on these links to download and save this video.

Comments  (4)

All Comments
To post a comment, you'll need to login.
If you don't have an Esri Global Login ID, please register here.
Here is the video on Youtube. The resolution is great with this one!
https://www.youtube.com/watch?v=rAgqTi8Ko4A
pdallas09 1 Week ago
Report
Would be great if I could see anything
rmalo 3 Weeks ago
Report
I agree the resolution is very poor. Please enhance.
Johno79gis 4 Weeks ago
Report
This would be a great tutorial if I could see what was going on with the code. The same as the tutorials posted on Youtube. Were they recorded with cine cameras? More resolution please.
MattOKeeffe 9 Months ago
Report
  • 4 total