View Full Version : Modelling a (simple) Model Engine

Andrew Brown
11-15-2007, 06:34 AM
Hello fellow LightWave users,

I am trying to model a model aero engine, which should not be that difficult. If I attempt this from first principles, then the time factor is enormous. How would you best tackle the challenge (viewport pictures attached) so I can proceed?

I started with the cooling fins by making a subpatch box - but lost the plot due to the curvature on all axis. Then I tried lofting - great for the sides, but left me with 2 polys at the top and bottom that just could not be easily manipulated. With splines, all I get is an error message that they are not connected (or similar). It would be nice if I could just trace the image in 3D space, press a button and wow there's the mesh. If I perform boolean union and subtraction, then I am left with ugly geometry.

Normally I model electronic components (attached) but these are made by importing illustrator curves, extruding, performing boolean operations and rounding. This motor is a real challenge! Any help or suggestions anyone?

11-15-2007, 07:07 AM
I'd got for "hand-modelling" using primitives and lots of drill, slice and extrude myself. I'd like as not use splines or subpatches except for areas that are seriously curvy.

The easiest way is to think of how it is constructed, then break it down into pieces. After all, it isn't one single item, but many. Tackle one part, as you get more comfy, you'll find the others start to come to you.

11-15-2007, 07:18 AM
Yeah, when you break it down into small parts, the individual components look pretty easy to build. Screws and shafts and plates, etc., can be knocked out pretty quick. Then just glue them together.

Andrew Brown
11-15-2007, 07:22 AM
Hi Colkai, thanks for the input. Doing as you suggested - even with a high poly count leaves a lot of broken geometry, and it is not smooth. The engine cowling is smooth, so I should go for subpatching - unfortunately, this is where I am failing to get the job done in any reasonable time frame. Look at the two end pieces of geometry on the top cooling fins, here I have a 3D curve and a half round hole for the screw. How should I best mode this so the overall effect is smooth? Also, the cylinder head itself is not perfectly round - more a square with rounded corners.

11-15-2007, 08:09 AM
It would be nice if I could just trace the image in 3D space, press a button and wow there's the mesh.

There is something for tracing 2 color images and is called ImageForm, but your object is too complex to trace it nicely in one go.. ImageForm was later replaced by FormEditor and now by EasySpline.. Every of them are part of our TrueArt's Modeling Pack http://modelingpack.trueart.eu

Andrew Brown
11-15-2007, 08:14 AM
Hello Sensei,
Thanks for the pointer, but seems though that the plugins are for a PeeCee, I'm on a MAC!

11-15-2007, 08:19 AM
Almost the all commercial plug-ins are for Mac PowerPC too..
ImageForm was the first Mac ported plug-in in 2003.
EasySpline http://www.easyspline.com recently got spline & points highlighting feature too and everything is like in Windows version..

Andrew Brown
11-15-2007, 08:31 AM
Hi Sensei,
My mistake - I just went to the download page and saw a bunch of plugs for the PC only - and assumed... etc.
Really, I want to tackle the task w/o the plug - so, from LW only. Seems I'll have to subpatch the individual elements, freeze then boolean etc. Only problem I have with that approach is the inability to get nice bevels on the edges. Rounder just crashes even though I have merged points etc. Guess the freezing made the geometry way too complex.

11-15-2007, 08:55 AM
Hi Colkai, thanks for the input. Doing as you suggested - even with a high poly count leaves a lot of broken geometry
Do you mean broken as in not joined together, or as in bad?

I would expect parts to be 'joined' but not actually be part of the same mesh, rather like say a teapot and it's lid. If you mean bad, check for non planars as they are usually the problem, those and 1 & 2 point polys.

If you wander over to LWG3D and check out the Serenity model, you can see that is really complex, but is actually made up of many parts and in my mind, it should be the same to do this sort of thing. Not that I've done an engine yet mind you. ;)

Andrew Brown
11-15-2007, 09:16 AM
'broken' as in not smooth - and with holes - and yes, it's those non planars. The solution I have so far is to mold the shape (cylinder head) in sub-patch mode, freeze the geometry and then boolean etc. I am not happy with that approach however, but because time is against me, this seems to be the only option I have. Down side of this is that I have an impressive no. of polygons. A mesh would have been far easier, but I am short of a solution. If I look at Sensei's car, the poly count is really low - and the model is not trivial. Surely, this can also be performed in LW without a third-party plug?

11-15-2007, 09:52 AM
My car is spline model.. It's EasySpline which is showing white virtual geometry.. If you look at Statistics window on right bottom, there is just 428 points in 70 splines (so we can say it's low poly ;) ), but they will be frozen to something like 10,000 polys at the end of modeling..

11-15-2007, 10:51 AM
Hi Andrew !

Every subject for modeling which have such good blueprints it's "easy" to model :). I'd "kill" for such hi-res qualit BPs when i start to model industiral stuff. But often i get none or very band/low res ones :(.

I'd start with simple shapes and use Extender, multishift and bandsaw/bevel to make nice Subds model at the end.

11-15-2007, 12:25 PM
I would go with subpatches as well. My tutorial (free) is geared toward inorganic modeling and should give you some ideas.

11-15-2007, 12:45 PM
Also looking at your post again. I would break the engine down into primitive shapes first. That this from a modeling perspective identify the parts of the model that could be made separately first and then join them as a subpatch object. Other parts may or may not have to be joined.

For instance, this is how I see it.

1) You have a main body that is a cylinder with detail added. Similar to something you could create as a lathe operation then add things to it.

2) There is a vertical piece - another cylinder - coming out of the main body with some detail added ( other primitive shapes)

3) Above that is a rounded cube with the heat fins.

4) At an angle there is another cylinder coming out of the main body.

And finally there are more primitive shapes attached to these main objects.

The objective would be to start with the big primitive shapes and create the main body of them with an eye to where and how they would have the detail added.

Then I would start on the smaller parts that stick out of the main body creating each separately then attaching them.

I go into the very basics of how to do this (very basic) in my tutorial. These basics could be expanded on for a project like this. I would love to do this as a tutorial for Lightwiki but I am in the middle of a large project now. In any case if you take the principles I outline you could do it.

Andrew Brown
11-16-2007, 01:43 AM
Thanks Lewis for your advice here, and yes I am playing with primitives to get the basic form before freezing and then performing boolean operations etc. The LW patch should? be up to this, shouldn't it? Unfortunately, although I can draw the splines, there is no way I can see how to follow the advice in the user's guide to create a volumetric form.

Thanks also to Surrealist. I am using your techniques and find them an excellent source of inspiration when subpatching. Perhaps you have a trick up your sleeve that you can share with me (us) to bore a semi-circular hole in the geometry.

11-16-2007, 01:49 AM
IMHO on this model you don't need to FREEZE anything :). I'd do it as FULL SubDS, it'll take little more time to weld and merge all points after drilling/boleaning but result will be great ;).

11-16-2007, 02:00 AM
BTW do you have dimensions of that engine ? Lenght ? Height and Width ?

Andrew Brown
11-16-2007, 07:36 AM
Actually Lewis, I have. The attached PDF shows the engine in all its glory, and, not being protected, allowed me to open it in Illustrator, tidy up the image and copy the view to Photoshop for the viewports. I would love to do the whole thing in Subpatch mode, but I am too inexperienced to get a satisfactory 3D mesh together - hence my original post. Also, I have problems with those semi-circular holes. Hence, I created subpatch models of some of the geometry, froze it and then performed the relevant boolean operations. If you have a better solution, then I am all ears! I do not wish to get a 3rd party plug - just yet.

11-16-2007, 08:04 AM
I don't think so in this project help you any 3rd party plug-in except your own experience.. And to get experience you need to model for months or years everyday easier things to get used to and learn all tricks..

11-16-2007, 08:11 AM
There is no "magic" it's just practice, in subDs you can make aynthing with carefull planing and having right number of polygons (not too much but not too low either) :).

This PDF is great resource and all what you need to do now is setup BPs in modeler and start making bolts/screws and other parts. Just make BOX with exact size of outer boundaries of engine/model and CUT images for background at their edges so they are sized as maximim size od engine. Then go to background settings in modeler and set each image to it's window (Top, Front, Side) but be sure that you are having BOX model with dimensions in background layer. That will alow you to hit "automatic size" button in Background image settings and LW will automatically resize your images to fit BOX you made so BPs will match as close as possible :).

11-16-2007, 03:07 PM
I am not sure what simi-circle holes you are talking about. ( at the top in the fins?) I'd be glad to help you with ideas on that.

I have a suggestion though. Why not start with a simple part of it to do in subpatches? Just pick any part but pick something you think you can do. If you have questions on how to approach that part post it and we can help.

I think it is going to be involved no matter how you approach it. I might be inclined to start with the main body first. It seems simplest.

Then as you move along it would be then a matter of attaching those parts - planning here would be good of course but I think you can do it.

11-16-2007, 06:00 PM
Awesome ref pics. I've been looking for a cool new project to practice on! My dad and I used OS engines exclusively for our planes way back in the day - great products. And thanks to Surrealist, I've got a new hammer to render it with... :D

There's obviously an excessive amount of "round" on the model, but this could be a good 'either/or' discussion of SubD vs. polygonal. You would definately give Multishift a workout. End results would definately be better with SubD's imo, but I'd say it would be quite a bit more work on getting all those edges boxed out. Preference vs. results vs. time - as usual I guess... but remember; There's usually never enough time to do it right the first time, but someone always makes time for you to fix it when it's wrong.

11-16-2007, 06:17 PM
Of course, after looking at the PDF, you could always make each part and assemble as designed (since they seem to give you the entire breakdown). Smaller simpler parts vs. trying to sculpt the finished product out of bigger shapes. Just a thought.

Andrew Brown
11-19-2007, 05:17 AM
Thanks to all for their encouragement so far. I have attached a small render of the cylinder head - just to illustrate that without subpatches, the realism just won't be there. The hex screws and top nut are all subpatched to get those nice tight curves. An immediate observation is that the holes in the fins are too sharp and there isn't any filleting at the base of any of the cooling fins. So, looks like I'll have to start with a square, bandsaw it in the x and z planes, and then stencil other square primitives on to the surface - one for each of the cooling fins. Then I can bevel the geometry and hope that the result looks close to the real thing. is there really not a short cut here?

11-19-2007, 05:24 AM
It's a good start very good and yes i'd also make all as SubDs :). You can add small bevels to edges of normal polys (non subDs) if you want but you will be more happy with subDs ;).

11-19-2007, 08:03 AM
But it still looks great Andrew. Nice work so far.

11-19-2007, 02:58 PM
T. is there really not a short cut here?

If you look at the top veiw it is easy to see that you can split it up into 1/4 sections. Cut everything back to 1/4 and do all your editing of the polyflow so you have sight subd edges and so on, then mirror twice.

What I would do for something like this part is first plot out the polyflow on a flat plane then extude it with Extender plus.

This is by no means perfect but it shows the process.

To control the flange just adjust the bottom ring.

11-19-2007, 03:00 PM
Control Ring (loop) for flange.

11-19-2007, 03:10 PM

And also another detail I omitted was the rounded tops. That would be just a matter of adjusting the polyflow on the top for that.

11-20-2007, 02:34 AM
Lovely mini-tut on how to tackle these things there Surrealist. :)

11-20-2007, 05:14 AM
is there really not a short cut here?

At the risk of going off-topic, Andrew, the long-term solution is to acquire some other software that's better suited to modeling these kind of forms. I've mentioned Form Z already, but there's Rhino, modo, Concepts Unlimited...I could go on.

All due respect to Surrealist for his informative tutorial, but modeling these kind of hard-surface forms using a subpatch modeler is like drafting with a paintbrush.

Andrew Brown
11-20-2007, 05:20 AM
I agree with colkai, a nice mini tutorial. I too drew a similar conclusion and I tried, as you did, Surrealist, to map out the geometry and then extend it. I based the mapping on the tutorial you gave for the letter 'S'. Unfortunately, the fillets blend in with the edge of the cylinder head - making mapping somewhat of a nightmare, and after some hours tweaking I gave up on the idea. Instead, I created a number of box primitives, beveled the edges and pulled the centres up. Later I knifed the geometry to get control handles for the curvature of the fillets and fin radius. This was much faster - an order of a few minutes. You just have to remember to look in the point info panel to see where the base point are. The next step was to create a flat subpatch plane for the base upon which the fins stood and pulled the points on to the same position as the start of the fillets. The effect is clean - more images of the progress will follow. But for now, thanks to all your support.

Andrew Brown
11-20-2007, 05:28 AM
Thanks, Giacomo99, but I will try to stick with LW for the time being. Yes, Surrealist's solution is time consuming and somewhat long winded if you are unfamiliar with this type of construction. If you know your tools, then this perhaps is the fastest way to a solution. I am not familiar with the other progs. you mentioned - I could equally well create an IGIS model in Inventor and then just texture the thing and set up the scene - but that too is diverging. If I really get stuck, then I'll consider an alternative.

Andrew Brown
11-20-2007, 08:40 AM
So, following the tips and intuition, I have 2 more test renders of the top part of the cylinder head that clearly show the micro bevels and filleting. Still a bit of 'pinching' at the bottom of the left and right-hand fins though. The whole model thus far is sub patched - goal achieved! Only I would have preferred a less manually intensive approach to get the model to this stage. Now for some other parts.

11-20-2007, 02:45 PM
Thanks to Colkai, of course. :)

All I can say is: Nice!

The reasoning behind my approach has more to do with the base polyflow, and doing that while it is still flat and unobstructed so I am interested in your wires and how you did that. Always interested in different approaches and ways to get to the polyflow faster.

The key thing with subpatches - in any program - is polyflow.

Just looking real good. Keep it up. I think you have the idea.

If you run into any more snags let us know and by all means share any insights you have along the way. :)

11-20-2007, 11:19 PM
Always interested in different approaches and ways to get to the polyflow faster.

How are you liking EasyMesh approach then.. :) http://www2.trueart.pl/Products/Plug-Ins/EasyMesh/Graphics/Movies/EasyMesh_1.mov

11-21-2007, 12:18 AM
Interesting. Very cool plugin. For some things that would be very handy. :)

Andrew Brown
12-10-2007, 02:46 AM
Well, I have applied the techniques picked up in this forum and have managed to get the model nearly complete - the texturing is still not quite to my liking - but that is a small issue!

How long should a subject like this take?

Does anyone know how to produce a low(ish) poly count screw thread? I have seen tutorials taking a triangle and hit and miss getting a screw effect using the lathe tool. What I did was to draw a perfect sine wave, clone it the required amount of times along an axis, stencil it onto a flat poly, remove one half (looks like a comb) lathe the poly with one rotation and an offset equal to the length of the original sine wave. The resulting geometry was then boolean subtracted from the shaft. Are there any better ways of doing this?


12-10-2007, 03:32 PM
Nice job man. Very nice. I have never done screw threads so I'll be no help there. Keep up the great work!

Andrew Brown
12-12-2007, 10:16 AM
... and here with reference background

12-12-2007, 12:26 PM
Very impressive work.

12-12-2007, 02:42 PM
really nice work on the engine!!

In my next video tutorial, I'll be showing how to do the threads on a bottle (as well as the bottle) in subd, which would prob. be the same as a screw thread... look for it some time this weekend or so... link in my sig... (don't know how low poly you'll consider it but it might help)


02-25-2008, 04:39 AM
nice model.
where is the background from? Ive seen this a few times

You can find it here along with a load of nice node presets