PDA

View Full Version : Hot air balloon driving me crazy



Traveler
09-23-2004, 04:38 PM
A saw this tutorial (http://67.15.36.49/team/Tutorials/max_ballon/max_ballon.asp) a few weeks ago and figured it couldn't be too difficult to do. Although the balloon was made with 3dmax, I thought Lightwave should've been able to do the trick as well. After having tried and failed several times now in the last three evenings, I'm starting to get a little bit annoyed. :( (but even more motivated).

I thought splines would work best in this case. So after a few trials I got a shape which looked kinda like in the tutorial. (see first 2 steps in image below).
Next step, (which in the tut seemed like an easy one) get those polys in.
Well here's where I'm lost. At first I thought rail extrude would be of some help, but after some really awkward results I went looking for something else.

I figured I could add more splines and then let (auto) patch do the rest. Part three of the images shows the finished spline cage. Part four shows what happend after auto patch. Needless to say, I was a bit disappointed, what has happend here?

Anyway, I figured I must have done something wrong when creating the splines so I remade the model from cratch. Today I got at the same point, but again (auto) patching didn't work. I didn't want to redo the entire thing again, so I removed the wrong polys (a lot of em:() and manually added new ones. (I then realized that smaller selections did work when using (auto)patch).

image 5 shows a really poor endresult which clearly shows mistake in the model. It doesn't look at all like the image in the tutorial. The sides need to be less bumpier (not sure if that's the correct word, but I hope you understand) and shaper where they meet.

Now,.. the questions. I want to try this again. How do I start and what am I missing in my previous attempts. My current model has about 85 curves. I've learned that a balloon like this one has actually 24 sides, which will increase the number of curves to about 100. Isn't there any way to create this shape automatically? I mean, it looks so simple, but right now it takes me hours to do.
Also, what am I doing wrong with (auto) patch. Is my model incompatible, or wasn't (auto) patch designed to do stuff like this.

Many thanks in advance.

cresshead
09-23-2004, 05:27 PM
not tried it but i would have done this with a disc...
beveled it...to form the ballon shape
selected every other point and scaled it in to get the shape sorted...
maybe also used bandsaw to tighten up the stitched areas...

hit the tab key for sub d n your done...10 min job possibly

try that...!

cresshead
09-23-2004, 07:38 PM
yeah bevel worked fine...
and a wee bit of bandsaw too tighten up the seams

Traveler
09-24-2004, 01:56 AM
10 minutes?! Oh man, the time I've wasted.... Well not entirely wasted, cause I did learn a few new things, but still.
In any case, huge thanks for putting my mind in a new direction. I guess the shots in the tut narrowed my thinking.

I'll give this one another try later today.

cresshead
09-24-2004, 07:12 AM
note:

i made a 48 segment disc
created the balloon basic shape with bevel
then deleted 3/4 of the disc so i didn't have too much work to bandsaw...
just a 90 deg arc....
then mirrored and mirrored again to re create the 360 deg balloon shape.

it took longer than 10 mins...about 30 mins of playing with ideas then mapped the
balloon and made a simple basket.


--there's a wire shot i the WIP section of the newtek forums to look at too--

GregMalick
09-24-2004, 03:07 PM
cresshead,
I got lost at "deleted 3/4 of the disk".
Could you post a few pictures of the technique.
I guess I'm a little dull. :o

cresshead
09-24-2004, 03:17 PM
yeah will do...gotta nip out for some milk for my cuppa tea!...ran out!¬

okay...got me milk!

right.

1create a disc 48 sides
2.extrude slightly
2a.select top poly of the disc
3.use bevel multiple times to make the balloon evnvelope
4.delete the botom and top disc polys 48 sided polys...
5.you can now use tab key for sub patching...no 4plus poly error...though you do have a hole in the top and bottom of your balloon currently...no problem fix it later!
6.from the side view select points for area where you want the balloon envelop to be scaled in..
7.top view de select points not needed...there's load of ways to select the points you want...so use your judgement here...which ever way works for ya...
8.scale them in...either with h for stretch and use the diagonal to get a 2d scale
or use shift h for scale...oh n set your "mode" to centre of origin as you have made your balloon at 0 0 0 right??

9.hit tab key for sub d's...

10.now currently you have a pretty good balloon envelope but it isn't "defined"
well where the stitching would be is it....

11.you need to use bandsaw to add detail either side of each piece of the cloth..
for each segment...this can get tricky to know what's been selected...

12.....so i spent a min or two making every other cloth area that would be needed to be band sawed a different color...so i had alternate blu and white..
read on though!

13...my fav number!.....now then seeing as this is a regular shape and can be divided up either in half or quarters in top view you can cut down on the amout of bandsaw ops by only band sawing a quarter of the balloon....

so..

14.only select a quater and copy it to a new layer...
then

15.bandsaw each segment so there's two "cuts" at either side...quite small..like 0.01 and 0.09 repeat this for each segment.

once done...

16. mirror on x
17.mirror on y

18.m for merge to make sure you have no dup or stray points

19. select the top of the balloon point and h for stetch on x
20.h for strach on z
21.with point still selected merge points "m"....give it one surface colur agai if you wish...

save your balloon

happy ballooning!

SplineGod
09-25-2004, 01:05 AM
Actually all you have to do is make your template poly. Make two splines that are the shape of the balloons contour and do a rail extrude.

Traveler
09-25-2004, 05:56 PM
As said I would do, I've given this baby another try and fortunately it went a lot better this time. (And a whole lot faster too :) )

But allthough I am happy with the current solution. I do wish to know if splines work as well. SplineGod, in regards to your last post, could you be more specific? I have tried rail extrude a few times, but it didn't work for me.

Thanks.

SplineGod
09-25-2004, 06:53 PM
If you use more then one spline its called a multi rail extrude. The poly will conform to the average of both. In this case I used two splines by mirroring one over. :)

Hervé
09-26-2004, 02:49 AM
Larry's teknik is so far the best and the fastest... :D

cresshead
09-26-2004, 04:09 AM
re rail extrude

you place a poly shape in top view of the balloon then make a profile in left or back view..this is an open spline line...
then mirror it across...to make the l n r profile of the balloon
the top most point of the two profile lines is where you will line up your shape to so it fits in between them in left view

then hit rail extrude..you can leave it on auto or you can manually decide on the number of knots/segments etc...

if you find your rail extrude goes the "wrong way" and doesn't grow along the profiles...simply undo the extrude and FLIP [f shortcut key] the poly then try the rail extrude again

the good thing about rail extrude is it's pretty fast to setup and use
the bad thing [possibly] is that there's a certain amount of automisation to the creation of your model..

with the bevel method you have "total control" of where you want each segment
in the profile view and how many of them as you build it.
your also building a 3d model as you go..which for some people is better to see what they are getting built realtime in the viewport.

both methods "get you there"!

Traveler
09-26-2004, 06:07 AM
Larry's teknik is so far the best and the fastest...
I'd say that's a matter of opinion. Personally I like the other solution better. Somehow it feels as if I have more control over the entire shape.

In any case, thanks again for the replies! I now know what i did wrong in my previous attempts. Perhaps, if I had read the manual a bit better, I probably could've figured it out a lot sooner. :o

There was still one thing that kept me puzzled for a bit though.
Image A, shows an incorrect rail extrude. Whatever option I tried, I couldn't get the correct shape. I then tried the sample in the book with image B as the result: a shape that matches the lines perfectly. So what has caused the first attempt to look like image A?

The solution is the disc, it was placed a bit below the splines' starting points. Placing it above it did the trick :)

cresshead
09-26-2004, 06:22 AM
yeah placement of the disc is a critical aspect which will result in your model following the spline guides correctly.

as you can see modeler/lightwave has a host of tools that can facilitate your
ideas into 3d forms there's so many "methods" all you need is to find the one that
makes your ideas translate into the 3d form with the least pain/time but uppermost accuracy in the result.

steve g

colkai
09-27-2004, 05:58 AM
yeah placement of the disc is a critical aspect which will result in your model following the spline guides correctly.

This can be made easier by using the AlignToRail plugin, but I can't seem to find its URL on Flay any more. Though Pictrix 'First Contact' http://www.pictrix.jp/lw/C1st/index.html is similar, and allows a little more control. Not sure if it's good for multiple rails though.