How to Grow Your Family

How to grow your family: Making use of models created in 3D studio or AutoCAD

With the family content fairly light in revit, it seems to me that a good source of pre-modelled objects is that of 3D studio and AutoCAD. There are an abundance of well drawn, readily available objects that can be used in revit as a quick fix for that awkward to model, time consuming family. The only real downside can be that they can be heavy in file size (depends on the complexity of the original) and they lack the parametric qualities that makes a true, well constructed revit family so flexible.

From the links page here at Revitcity is a link to the '3d cafe' website. This is a great source of material and where I started this tutorial.

1. Identify and download the object you desire. This is usually a zip file and for the purpose of this exercise, I will assume it is in a .3ds file format. (also that you know how to unzip and locate the file).

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2. Open your copy of 3D studio Max or Viz, and go to 'file', 'import', then select the file you have just unzipped. Select 'completely replace screen'.

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3. Once open, go to 'file', 'export' then select a location and name for your file. Most importantly, select the file format as either AutoCAD dwg, or dxf (doesn't matter which). You will be prompted as to which version of AutoCAD (2004 or 2000 being the most common). Make sue all the boxes are ticked then click 'ok'.

4. Open your version of AutoCAD. Find and open the file you have just created.

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It's easiest to work with from one of the isometric views - 'view', '3d views', 'sw isometric' for example.

5. Normally it is exported as a block, explode this only once. This should leave the block as made up as a series of individual meshes which normally will relate to groups of materials (for instance, the tires will be part of one mesh, the windscreen and windows part of another etc. Without picking a command, simply touch objects so the grips appear thus showing you the grouping.

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You will notice that there may be other miscellaneous objects exported alongside, simply delete those that are not necessary. Select the whole of the remaining objects and make them 'bylayer in colour'

6. Create new layers: You will find that there is usually only one layer within the dwg. For later use, its best to create a series of new layers (I name them to correspond with the material I will later apply in Revit), for instance, 'Toyota paintwork', 'Toyota glass', 'Toyota wheels' etc. For ease of viewing, ensure these have all different colours (the actual colour is irrelevant unless you are very fussy!).

7. Once the layers are created (normally no more than seven or eight are needed), you need to pick the individual meshes, one at a time and assign them to those layers. I find it easiest to start with all layers switched off except for the layer the object started in. Then, for example, select the main bodywork , and assign the new layer to it. You will see it then disappears (as the new layer it has gone on to was switched off) thus just leaving the objects that you still need to assign a layer to.

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8. Once all the objects have disappeared (it takes a few minutes), switch everything back on and take a look. Type 'shade' to view it as a shaded object if you prefer. Try to see that your material distribution matches that of the real object. (For many of the cars I have imported, I will check out the manufacturers websites to see images of what material goes where on the real vehicle for an authentic visualisation). Save the file, close AutoCAD.

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9. Finally you get to use revit! Open it up and go to 'file', 'new', 'family' and open up the 'metric generic model' family template. Then go 'file', 'import/link', 'dwg'. Locate and select the file you have just created paying attention to the units it was created in (ie: meters, centimetres etc. If necessary, go back to the file to check.) Import object.

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10. Once imported, open up the floor plan view and position centrally on the reference planes. Check the side elevations to see it's wheels are actually on the ground! If not move it to the desired locations.

11. Go to 'settings', 'object styles', then the 'imported objects' tab. Here we will tell revit to assign materials to those AutoCAD layers we created earlier. To do this, simply select the layer name under the 'category' heading, then select the adjacent material under the 'material' tab. Now you should be in the material editor and the final straight.

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For example: for the layer named tyres, select to create a new material called 'tyres', then associate an appropriate texture for it. Personally I create a new material for each of the layers I have created, then assign the render map I want individually to each one. This helps in a project where you may use for example 'glass' as a material name, but want it to display in different ways depending on the object. Finish off assigning all layers with materials.

12. Enjoy the results. Place the family in a 'test showroom' project ( big enclosed area with good lighting etc) and see if you like it.

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If once rendered, you are not happy with the material selection, go back to the family and edit it there. If however you have assigned meshes to the wrong layers whilst in Autocad, go back to your dwg file and alter it there, then re-import the file into the family you have already created, deleting the previous imported dwg. That way you will not need to re-assign materials.

Useful tip:

Setting up all the layers in AutoCAD, then assigning the materials within revit is a bit laborious. However, you should only need to do this once. Next time you download a 3ds file, export it from 3D studio into AutoCAD as before. This time, open up your existing dwg file (this will become a template file for you) where you have already created all the layers and import the new object into it. 'Save as' a new file, delete the old unwanted objects then simply assign all the meshes to the already created layers as before. Similarly, once you have assigned your layers to the meshes, open up your existing revit family, import your new dwg into it. 'Save as' the file to a new name, delete out the old imported dwg, then the new dwg's layers will already be assigned to materials. (another template file for you.)

I hope this will be useful to you all, don't forget about all the other content which can be taken from other software packages and converted through dwg or dxf. Good luck!