• 3D speed

This Article describes how to troubleshoot 3D performance problems

Polygon Count

The most typical reason for poor 3D performance is the large number of polygons in the 3D model. Not however, that it is not the only contributing factor. As a rule of thumb, a model is "large" when polygon count reaches 1 million, and the performance problems turn severe in the 3-4 million region.

How to check model size

The easiest way to check model size is to use the Polygon counting tool, which you can download from the "ArchiCAD Goodies" site, available from ArchiCAD's help menu. The PolyCount palette will list ArchiCAD elements by type, and displays the number of polygons each element type represents in the project. Library parts are listed by object type - you will many times find that library parts make up for 80-90% of the project

Reducing model size

First of all, make sure that only elements that you really need are displayed in the 3D view:

• Make sure you turn off unnecessary layers, e.g. layers of elements that you do not even see in 3D - e.g. interior walls and furniture, site improvements, etc... Save a Layer combination that you use for working in 3D

• Use the Filter elements in 3D feature (It's in View menu/Elements in 3D view) to turn off element types you do no really need - You might not always need Lamps, Curtain Walls, sometimes not even doors and windows when working in 3D. You can also set here which stories you want to see - you might not need all of them all the time.

• Use the Marquee tool or the 3D Cutting Planes to show only a part of your model.

• Some objects have different 3D detail level settings. You can temporarily set this to "Simple" instead of "Detailed" when working in 3D. (Note that you can set the detail level in the the PolyCount palette of the Polygon Counting tool) Similarly, curved objects typically have a "resolution" parameter. You can set it as low as possible without having a major effect on what you see in 3D. Also, some elements have extra fittings that you might also turn off temporarily - e.g. the door handles, stair railings, etc...

• Curtain walls have a Model View Option for "Full" or "Schematic"

• The resolution of elements that had been created with the Magic Wand tool can be controlled by the Magic Wand settings (prior creation). Make sure large slabs, meshes, etc... are not over-detailed.

Problem elements

Element types that most typically contribute to large number of polygons:

• Trees and plants - consider that each leaf is an individual polygon - and if shadow casting is on, then leafs cast shadow on each other, creating a vast amount of shadow polygons. Instead of using trees, you might consider using the "Tree Bitmap" object, which is a single polygon with an image applied as a texture. You can even use your own images to customize this object. (See details in TechNotes/How to put custom images to default bitmap people) Using Alpha Channel, you can achieve proper shadow casting with this object. You can also use other tricks to reduce model size, like Link Ellis's rendering tip: TechNotes/Speed up Rendering

• objects from other applications - e.g. objects imported from Cinema4D or 3DStudio, which were modeled in a completely different scale and are over-detailed compared to their significance in the ArchiCAD model. A boat or a car that was modeled to display all the fine details of the vehicle might just be too much to include in your ArchiCAD model.

• Meshes - If the mesh was created based on survey data with a fine scale, it might prove over-detailed in ArchiCAD. Consider what detail do you really need for the mesh.

• Curtain walls - curtain walls are complex, and can be overcomplicated with custom frames, junctions and accessories. You always have the option to display them in "Schematic" mode when you don't need all the details.

• Elements with Complex Profile - If the profile is complex, it will increase the overall polygon of the wall, beam or column it is applied to.

• Accessories - again, watch out for the fine details. If you only need the details for 3D visualization, you might consider applying a custom material with a photo image of the details as texture on the wall/slab/roof instead of actually modeling all the details.

Polygon count of certain element types

Element interactions

It may happen that even though the polygon count of your model is not high, it still takes an unusually long time to display it in 3D. In this case there are probably element interactions that take long to calculate. First determine if the problem is caused by GDL elements or other ArchiCAD building elements. Using the Filter elements in 3D command turn off doors, windows, objects, lamps and curtain walls to determine if they cause the slowness or not. If they do, try to determine which cause the problem by turning off/deleting them type by type.

If your project is still slow even without GDL objects, then try unchecking the Enhanced connections for Walls and Beams option in the Options/Project Preferences/Construction Elements settings. This might change how your model look, e.g. if you have connecting walls with different height. If you only have equal height walls, then turning off this setting may boost the 3D performance.

If none of the above helps, you most likely have a problem with Solid Element Operations. Solid element operations are either created automatically (when slabs cut walls, columns cut beams, etc...) or by the user, using the Solid Element Operations... command. They create links between elements that need to be calculated when the 3D model is generated or changed. Solid Element Operations may slow down the project if:

* they are present in large number (thousands of elements are involved) * one or more of the involved elements are very complex (such as meshes, large complex profile walls) * the result of the solid operation creates a degenerated (geometrically not sound) body.

To find which elements cause the problem, follow these steps:

• Make a copy of the file, so you have an original copy and an other copy that you can experiment with

• Use the Filter elements in 3D function to turn off element types one by one. This will help you determine which type of elements causes the problem

• If you found the "bad" element type, hide all other element type, and check if 3D rebuild is still slow. You might find that e.g. if you show slabs only, that's fast, if you show walls only, that's also fast, but if you show slabs AND walls, then the model rebuilds slowly. This indicates that there is a Solid Element Operation between some slabs and walls that cause the problem

• Once you have determined the unsound element type(s), first check if there is any repetitive model component that are present in large numbers (e.g. fine details of stairs, railings, furniture or accessories modeled with small walls, slabs or beams. Such components should be saved as library objects)
• Then check if you have any elements with unusual size or shape. Try deleting these to determine if they are the culprit.

• Also look for any element with a complex profile. You can use the Find and Select tool to find such element, as it has a criteria for "Complex Profile"

Once you have found the problem elements, try canceling solid operations on them:

• Open the Solid Element Operations palette,
• Select he element(s),
• Use the "Cancel Operations of Selected Elements on..." options - press all three buttons: All targets; All Operators; All other Selected Elements

If you have found the problem element, and you also made sure that canceling the solid operation fixes the problem, try re-create the element and try re-establish the solid operation. This may fix the problem. If it does not, you have one last option to try fix the problem:

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