Dan's 3d Modeling optimisation tutorial

Preliminary notes: Some good looking models you see in Virtual Sailor drop the frame rate and make you feel that your brand new computer is in fact a 386. "yes but it's an hug model" you would say for some. NO ! the size of the models have nothing to do with. The fact is that those model aren't optimised and wast unseen polygon for nothing. I have seen model that had 16'000 polygon and looked less detailed than the arleigh. One last word: I apologies for my english but I think you will get the picture and this isn't an English learning tutorial. This said here we go:

Joygame Screenshot Content

Test a model
Removing polygon: easy
to be miserly: a short reflexion
Vertex VS Object work
Winch example
Cabin example (with model)
Choosing your goal
Final word
Homepage, Contact

Next Tutorial:
Texturing optimisation

Test a model

-For a model that don't have interior modelised go under the deck and look the sky

This is what you should see... sea and sky.
All the polygon that aren't seen in normal operation are removed. If you count that you have about the 1/2 count of poly under the deck without optimisation and same for the hull the arleigh would have been 4700 polygon hugh !!! a wast of 1600 polygon for NOTHING!
So rule number one: all the unseen polygon should be removed

(Highlight: what's exactly a polygon?)

Removing polygon: easy

We will add a cylinder on the deck that can figure everything you want.

Select the cylinder

  Hit "edit mesh"
  Sub object: Face
  selection: square

Select a bottom view and click on the object's bottom

Control with a perspective view seen from under the object that you have the right polygon selected and hit "Delete" on your keyboard. Reply "yes" at "remove isolated vertice" while it's the center vertex and we don't need it anymore. Et voila ! on a 64 polygon cylinder we drop to 48 polygon without any visual impact.
You should do that for any unseen polygon. If your gun's edge enter in a turret than remove the edge polygon.

one more time fot the pleasure ?: all the unseen polygon should be removed

to be miserly: a short reflexion

Before adding this marvelous winch you plan on the deck take sometime to think: Do you really need 800 polygon for a small object like this ? don't you preffer to add 10 winch with 100 polygon ? Of course you have also the choice to add 10 time a 800 polygon winch, but then the user will not use your model anymore. Player want smooth animation and not still picture in their game.

Example: constructing a winch, right and wrong method

First the body:

Remember 3dMax is intended for making animation movie at first so the default setting for constructing object are always to high for real time modelling. By default 3dmax put 24 side for a cylinder wich give a 96 polygon object. Far to high for a winch's body. we will drop this count to 8 side which make a 32 polygon object !!!. Of course for bigger object you can rise the count a bit but usually going further than 12 side will sound like a wast.

Vertex VS Object

For constructing a winch we can work at object level making 3 cylinder one on the other (base body and top) but this is really not the right method for a lot of reason.

This is why one should work every time it's possible at vertex level instead. We will now construct two winch one using a "newbies" method and one using the technique described before and also the vertex method.

Example: constructing a winch wrong method:

Total 288 polygon. "we are far from the 800 you described ?" No! Add the handle, make it look better with more object and we will reach the 800. Even if not 4 winch x 288 = 1152 poly 1/3 count of the arleigh. What about the rest of the boat ?

Example: constructing a winch right method:

First construct a cylinder object from top view using the setting shown: Height segment: 5, Side: 8.

Then go to edit mesh as shown below:

Then select the midle vertex from a side view, select the size tool, Select the top view, Select X,Y moving and downsize the vertex from the top view.

Move the vertex in the right place using the moving tool with the right direction setting to avoid error.

Well you get the picture ? this method avoid display error beetween object and don't wast polygon. 3d api also love to display object where all the polygon are connected by vertice this avoid changing state and avoid cycle wasting.

Hey ! Don't forget to remove unseen polygon. Hit delete here.

Total for now: 88 polygon VS 288 with previous method. And also the more object you have, more the count become dramatical. I recall also to you that at texturing time if you use "phong" shading your winch will look as good as the "newbies" one. The more an object is important and will be well seen the more your object should be detailed. If you make a winch simulator go on with 800 poly winch, if not focus on object that are more important. The vertex method need some reflection before building a complex object: how much division will I need ? but this method as well as the tips described before work same for all part of your model

consider building a cabin for your petrol boat:

Example: constructing a cabin wrong method:

Here we have five box. Even if they are well joigned there could still be display error beetween object.

Here we have also 14 wasted polygon on 60. Consider that if you texture the box the processsor will still work to texture those unseen polygon and surface. Hom many texel drawed ? and this is also a very simple example.

Click here to load this example: crappy cabin.max

Example: constructing a cabin right method: (make this things grow)

This method require some more reflection BEFORE drawing anythings, but while the start is slower you will gain time at the end when other will have headeach trying to remove error and wondering why theire model are so slow to display. Also this is not the only method but the result should be the same: a maximum of polygon sharing vertex and the less count possible of unseen surface.

First thing create a box with 3 lenght and 3 width: (here the base model : base cabin.max)

While selecting entire row of vertex from top view, start to move them in the right place. For symetrical row, select them all with CTL key and use the resize tool in one direction only.

Now go in face sub object mode select the two face shown below, click on extrude and drag or type a value

Make this things continue growing while selecting a face and extruding it

And so on until here

Here we are. Now we can polish our model using the unusued polygon to make it look more complex you will learn also one useful tool: Collapse. This tool merge two vertex and is very usefull also to remove polygon.
From the perspective view and in vertex mode, select the two vertex shown while keeping CTL key down...

and click on "Collapse"

Now collapse all those and make the same on the other side

Now use moving or sizing row vertex as you learn before and from different view to obtain the result below. (here you can load the model just before the final step: Cabin just before finishing.max)

Mhhh there is still missing something.... Ohhhhh of course REMOVE the unseen poly


This model is garanteed with no error display, no unseen poly, and should be better processed by the computer while there is no overlapping poly.
You will tell perhaps that the poly count show here 66 poly VS 60 with the other model... hey wait! this one is far more complex than the crappy one, how many more box to make this form with the crappy example ? at first thing I will tell four boxes. 4 x 12=48 60+48=108. So here is a better comparison :
108 overlapping poly + display error +unseen face processed
66 clean poly in 1 object without any error.

Click here to load the finished model: Cabin just after finishing.max

Choosing your goal

Of course you will not have the same goal for an hugh or a small model. on a dinghy you can have smooth small object that make 300-400 poly or even more, but this is innaceptable on one hugh model. The BEST model should not exceed 6000 polygon or 8000 poly on an OUTSTANDING well optimised model I mean the one that every 3d maker dream to have done. it's probably not your's if it's your first one. also when I say 8000 you can forget playing with it on medium machine. (p400) More often the goal of 4000 poly seem more realistic while we often outpass the goal we fixed. If your hull alone make 3000 poly for one hugh model open the trashcan and restart your model. Also avoid like the pest smoothing tool like bolean and smooth mesh they all generate hugh count of polygon and also a lot of error that are difficult to resolve.
Also feel lucky I recall one time when the goal was ... 100 polygon.

Final word

Making model is very enjoyable and not difficult once you get the method. But it's a long process that require a lot of try before a good and clean result. I hope my tutorial would have been benefit for you even it doesn't cover all the modeling process. and don't forget the most important things at each step : MAKE BACKUP!!!

Have fun !

Daniel Polli September 2001