Optimisation and Workflow

by Ian Ibbotson

Introduction

Experienced modellers seem to know exactly how to manage a project, from drawing in AutoCAD through using MAX/VIZ creation and modifying tools, lighting, viewing, materials and production techniques. They basically know where to start and where and when to stop. On top of this knowledge (through experience) they tend to have lots of assets at hand such as models, textures and techniques that work time and time again. They are efficient and have a knack for producing optimised scenes

Optimisation is the process whereby you limit the assets and functions available to a project (views, faces, models, modifiers) to the minimum needed to achieve the required result. This means that a STRATEGY is required before touching any buttons - generally working from the desired outputs and working backwards to plan how exactly you will model each element of the scene. The following bullet points point out some important issues regarding optimisation and work flow

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Horses for courses

AutoCAD vs. MAX/VIZ

Decide exactly what will be drawn in AutoCAD and what will be created in MAX/VIZ. Create a matrix of closed polygons for surfaces and position blocks for objects, all on a comprehensive layer system ready for importing into MAX/VIZ. Understand the relationship between the two systems and how to edit in AutoCAD and import distinct objects at any time. Limit the need to redraw in MAX/VIZ. Use modifiers and keep them 'open' if you think lines may change in AutoCAD. Set up protocols for layers in AutoCAD and objects in VIZ/MAX

Groundmodelling

Understand the different ways of creating surface landforms using a groundmodeller (meshes, grids, contours, 3D polilines or 'strings') and the particular type and level of detail required for the task. Detail is easy to remove, but once removed it is hard to restore. Also, survey data is only as detailed as the number of points taken on site. Define a boundary between design data and context data and separate the geometry so that you concentrate purely on the design data

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Assets at Hand

Models

Keep models of street furniture, people, cars etc in easy to find and well named folders. Keep material libraries for objects well cataloged

Maps

Keep texture maps in well cataloged folders and separate images that have been edited for use from those that need attention

Techniques

Keep a knowledge base of techniques in well cataloged reference system for easy addition and retrieval. Keep reference manuals at hand and references to relevant sections in the knowledge base

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Model what you see

Set camera views up right at the beginning of a project and use the views to manage what is to be modelled and the level of detail of the scene. A scene is like a theatre scene. What goes on behind the scene is of no consequence to the audience

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Level of detail

Decide on the level of detail depending on the outputs required. Do not have lots of detail in overview context / planning scenes and  use different scenes depending on the detail required. Plan carefully right from the start where you will lead the viewer and place high detail where it has most effect

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Face Management

Whilst modelling keep a close eye on the amount of faces on each object created. Feel proud of a scene that functions well and looks great with the least number of faces possible, not one that has thousands and thousands of faces that looks similar and functions poorly. In general try to have the least amount of faces in a scene and always know which objects have the most faces. Remember that it is Ok to have lots of detail, just that it needs to be in the appropriate place

Summary Info / Object Properties

Use the Summary Info dialog and the Object Properties dialog to continually check objects for the amount of faces on them

Basic parameters

When using standard primitives use the parameters in the Modifer Stack to optimise geometry before converting to an editable mesh

Loft parameters

Lofts are renowned for using lots of faces. With lofts in particular always make sure you use the least number of path and shape steps in the Skin Parameters

Subdivide and MultiRes modifiers

Use these modifiers to alter the level of detail on editable meshes. Even if an object has too many faces and is an editable mesh (as oppose to one with modifiers applied) you can still reduce the amount of faces using the MultiRes modifier

Face Normals

Checking Force 2-sided in the Viewport Configuration dialog and Render Scene dialog so that all faces display correctly and can be rendered does take system resources. Experienced modellers keep a handle on face normals and make sure they are facing the correct way. This can be achieved quite easily by using the Normal modifier and converting to editable mesh. Note, however, that geometry generated from AutoCAD can always have face normals facing in different directions (depending on which direction lines were drawn in AutoCAD) and that complicated geometry (a tree for example) will always have leaves facing different ways. For these reasons many modellers keep Force 2-sided on at all times

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Convert to Editable Meshes

In general, once an object has been modelled and optimised to the required state, convert it to an editable mesh. If modifiers are left on an object MAX/VIZ has to re-create them every time the scene opens. The speed of a scene can be increased by this simple procedure. Once an object has been modelled, make that decision

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Use of Images

3D landscape work more than architectural or civil design benefits from the use of images. Wherever possible use images for sides of buildings, vegetation, context environments etc. These can be far more convincing, can put the viewer into their 'own place' and can give more realism to the scene. The amount of faces reduced is usually huge, enabling more objects to populate the scene (many objects being a characteristic of landscapes)

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