Site Modeling with Sketchup

Our goal is to represent a site and design interventions for the purpose of our own understanding and communication with colleagues, clients and the public. We begin with our site model which was compiled from GIS data with a new grading scenario created, and then transferred to a 3d modeling environment. The particular facilities of 3d modeling tools, will permit us to continue in our site representation and to achieve a new level of articulation in representing critical aspects of our vision of the site and our proposals for it.

It is interesting to consider how useful it is to be able to organize ideas. To be able to do this in your own mind, is essential for understanding what is important and evaluating different combinations of ideas. It is the same with software, but software and its traces are much easier to see. While you are doing this tutorial keep your eye on the metaphors that Sketchup uses to help you keep your ideas organized. The Idea of Layers, Groups and Scenes in sketchup form an Information Model that we can use to build complex ideas from primitive geometric representations. If we learn to use the information model of sketchup, our three dimensional ideas about what is important on a site can be coaxed very easily to perform very complex and meaningful stories from our imagination!

This tutorial will use these goals as an opportunity to practice particular operations geared toward becoming more fluent with a 3d design tool. We hope by the end of this to have a decent level of comfort flying to different parts of the site and creating forms that express our ideas, all while creating a relaible, predictable structure for the 3d database that we are creating. We will continue to demonstrate these ideas using SketchUp, but these principles and techniques will apply in any 3d modeling package.

Fluency in Design Representation

Becomiong fluent in any expressive medium can take a little practice but it a requirement for anyone who aspires to mastery. In the area of 3d modeling, the chief barriers to fluency boil down to these problems:

1. Understand the Relationship of Entities, Layers and Groups
2. Become very comfortable in moving to a particular place and orientation within our model.
3. Develop habits of organizing information in our models so that we will our models will behave predictably and reliably even as they become very complicated.

Prerequisites

The sample model that we begin with in this tutorial was made using the techniques described in Beginning a Sketchup Site Model with Data from GIS. It is highly recommended that you follow look at the sketchup videos and the sketchup online help topics linked from that tutorial.

The sample Dataset

Rigit-Click Here to download the sample Data set> Expand the zip archive to your C:\temp\yourusername folder.

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Understanding Layers and Groups

It is very important to develop a rational structutre for your model. A 3d model will have a lot of geometry in it. We should understand how to use Layers organize our geometry thematically and how Groups let us structure our objects as an Object Hierarchy. Many people have to learn these things the hard way, by observing how, after a model becomes just a little complicated, the confusion caused by a poor structure will lead to a situation where it is easier to throw away the whole model and start over, than it is to track down and fix problems that arise from not structuring the model well in the first place.

Explore the Basic Layers, Groups and Entities of your Model

The key ideas to get out of this are that Layers can be used to control the visibility of groups of objects. YOu may have many groups organized in one or more layers. Groups are made up of primitive entities. The current layer is selected by punching the radio button next to it in the layers window. Although you may put primitieve entities in any layer you want, this can lead to confusion as the eintities in a group may be in one layer, and the group itself may be in another. If you don;t understand this, you will end up with a model where parts seem to appear and disappear unpredictably. Therefore, it is best to Use Layers to control the visibility of Grouped geometry But keep the default layer, Layer 0, active and draw all of your primitive geometry on layer 0.

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Becoming Comfortable with Locating your Cursor and Orientation in your Model

In all 3d modeling packages, controling the location of your cursor and the orientation of your model is critical to being able to represent the forms that are in your imagination. The challenge is that our computer screen is two dimensional, and yet we need to be able to place geometry in a 3d space. IN some modeling software packages, you control the placement of your drawing tools by constraining the mouse movement to specific planes or by setting up constraints to movement with snap settings that are adjusted according to layers and types of geometry. SketchUp, on the other hand, is designed so that most of your control of cursor movement can be controlled without taking your hand off of the mouse -- without frequent adjustment of a snap settings dialog. SketchUp's dependence on inferences, as opposed to explicit (and complex) menus of snap options and reference planes is a distinction that makes SketchUp a quick productivity tool whith which users can become very quick and fluent.

The cursor in SketchUp tends to jump to nearby vertices, edges and faces. These inferences can help us and also be very frustrating if our cursor jumps to locations that aren't where we want our cursor or new geometry to snap. As it happens, these snaps are much easier to deal with when we are zoomed in, and much more difficult to control if we are zoomed out. For this reason you often have to zoom in close to locate one end of a line, and then in the midst of draawing, zoom out with the middle scroll wheel, perhaps shifting the center of the view by double-clicking the scroll wheel to get to where you want to place the other end of the line, where you would zoom in again to place the other end exactly where you want it.

The fact that other geometry that is visible in the model can be frustrating, but you should realize that you can control what objects are attracting your mouse by reorienting your view so that the area behind your work is not filled with detail. Of course it is also good to have your model organized so that you can selectively make detail disappear by turning off layers or hiding objects.

Sketchup also uses the axes in the model to help to infer the direction of our movements in 3-space. For example, if we want to create a vertical line, we can drag in the direction of the Blue Axis. This can be confounded if there is a lot of detail behind the cursor that is attracting inferences. So, if we want to draw an inference from the blue axis, it if helpful to change the oriantation of the model by obiting to an elevation view so that we can pull our line up into the sky without anything behind it. We still may have problems if the orientation of our model in our window is such that the blue and green axes are in-line with eachother. Therefore, in order to comfortably control the movement of our cursor in Sketchup we must be aware of how the orientation of our model may at times enhance or confound Sketchup's Inference Engine.

Keeping Things Flat: Modeling on the Ground Plan Image

One of the important thing about sketchup is the way that it can do elegant things like extruding and dividing polygons, pulling up peaked roofs, and things like that. In order for these things to work, it is important to keep the bases of things flat and horizontal, and to keep their edges square if we intend them to be square. This is very difficult to do if we are atempting to make buildings on our terrain surface, since there are many areas on the terrain that are not horizontal. This is where the our ground plan layer comes in handy. YOu should do most of your basic modeling of buildings on the groundplan layer, then move your buildings to the terrain layer when they are roughly finished. THe building models may be adjusted when you get them to the terrain.

Another very useful use of the groundplan layer is for modeling of objects that you intend to use in Google Earth. Since Google Earth automatically drapes models onto the terrain surface, you should make sure that the absolute heigth of the foot of the building is at 0 -- the height of the ground plan.

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Beginning a Model and Understanding Groups

We want to explore a few schemes for locating a beer garden in the vicinity of our new baseball stadium. The beergarden will have a building, some tables and some trees. we will start by making our building with a naive approach to groups. Then we will get smart and think about how to use groups and layers.

Now lets do it right.

Playing with Benches, Trees and Microclimate

Now for a slight diversion. We want to enjoy a nice beer in the shade in the summer time, but we would rather be in the sun in the winter time. So we will investigate some different schemes for organizing our patio with trees and benches. We can use thes scehmes to explore and communicate some ideas about the plusses and minuses of each scenario with regard to microclimate. This will let us explore the use of components and shadow studies; but more importantly how we can create and manage complex hierachies of groups using the Outliner Window. We will explore components in the next tutorial.

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Working with Object Hierarchies

Our aim is to create several beergarden schemes and to compare the microclimate qualities of each one. We have created one beergarden scenario that includes a berrgarden, Trees and Benches. This model has a layer schema that lets us manage which pof these meaningful classes of objects is visible. Now we will make a group of this entire schema by selecting all of the trees, our beergarden and the benches and group them together. If we make a copy of this group, then we will effectively made a new instance of the beergarden scheme, and we can rearrange the elements as an experiment. The Object Outliner window in Sketchup provides a nice interface for look at and working with object hierarchies. IN the end we will see how, by understanding the way that groups and layers work together to control visibility of pieces of our model, you will understand how to deal with very complex systems of 3d ideas without having a nervous breakdown.

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Suggested Exercises:

Here are some things we did in lab that I haven't had time to write up yet: