3dCrafter Wheel Animation problem

[savv_nz]

Hi Guys, I've posted this over at UKTS as well but had no success so far - I've searched the forums both here and there and not found anyone else with the same problem so here goes.

I am currently working on a loco model and have started the animation process for the wheels and valve gear. However, at the half way point in the animation the wheels seem to skip back a frame and then continue onwards - I have reanimated them several times and consistently have the same result. The glitch in the animation does not affect the animation of the rods etc, just the wheel.

I was wondering if anyone had any thoughts? I am using 3dC 9.2.2 and 40 frames of animation (I have tried it with 8, 16, 32 and had the same result each time).

[mrennie]

Hi Guys, I've posted this over at UKTS as well but had no success so far - I've searched the forums both here and there and not found anyone else with the same problem so here goes.

I am currently working on a loco model and have started the animation process for the wheels and valve gear. However, at the half way point in the animation the wheels seem to skip back a frame and then continue onwards - I have reanimated them several times and consistently have the same result. The glitch in the animation does not affect the animation of the rods etc, just the wheel.

I was wondering if anyone had any thoughts? I am using 3dC 9.2.2 and 40 frames of animation (I have tried it with 8, 16, 32 and had the same result each time).

Hi Stefan,

I remember now that I had something similar happen once, where the animation skipped a frame. I fixed it by deleting the entire animation line for that group and doing it again, even though I did it the same way as before. It's as if 3DC had an invisible animation point somewhere along the line.
Do you set four animation dots like I do? (red starting one in the first slot 0, for the 12 o'clock position, then another in slot 10 for 3 o'clock, anotherin slot 20 for 6 o'clock, another in slot 30 for 9 o'clock, and the last in in step 40 for the 12 o'clock again).

Cheers,

Mike

P.S. How about posting a screenshot of that beautiful loco - I know people here will love it!

[savv_nz]

Hi Mike,
I've cleared the animation several times, right back to using a fresh model before I did any animating at all and it continues to hiccup at the half way mark, even if I do something silly like make the first 3/4 the rotation happen in half the frames then the last 1/4 in the last half, it hiccups at whatever I make the half way point without fail.
It's animated how you describe, turning 90 degrees every ten frames:


And here's the loco for the loco spotters

New Zealand Railways Class Ja

And one to show the detailing:

[mrennie]

Hi Mike,
I've cleared the animation several times, right back to using a fresh model before I did any animating at all and it continues to hiccup at the half way mark, even if I do something silly like make the first 3/4 the rotation happen in half the frames then the last 1/4 in the last half, it hiccups at whatever I make the half way point without fail.
It's animated how you describe, turning 90 degrees every ten frames:


And here's the loco for the loco spotters

Fantastic detailing ... I absolutely love it!

I don't have any more ideas for you on the animation problem. Except for one ... could you make a simple wheel from scratch, directly in 3DCrafter, animate it and see what happens? I'm just wondering if it's some side-effect of importing to 3DC from Lightwave.

[savv_nz]

I'm back from having tested 3dC modelled parts and animating those, my 3dC modelling knowledge is limited so I used a textured cylinder... and the same thing occurs. At the half way point in the animation it hiccups then continues on. Like the wheels it doesnt do it at the end point which would have been more natural I would have thought.

Wondering if perhaps it was just a problem with things rotating on the X axis, I deleted the animation from my cylinder and told it to rotate instead around the Z axis... and got the exact same result. A hiccup at the half way point. Being thorough I tried the Y, same thing.

So I then went and made an all new 3dCanvas file, Stuck in my cylinder and make a cube for the root object and.... same problem. It hiccups at the halfway point.

What I might go and try is re-exporting the animation on something I know works fine and see what happens then, I'll check in again later.

*EDITED* I can now report that it does it to things that were once working perfectly fine, so I would suspect something has gone bung with my .ia exporter...

*EDITED* Completely removed 3dC, reinstalled... same problem. Hmm...

[savv_nz]

Just thought that I would update, the bumpy wheel is gone after boosting my animation frames first to 600 - on a suggestion from the guys at UKTS. I have since narrowed the frames down to 60 and still have a nice even rotation without a strange bump at the 180 degree mark.
I will now be able to press on with the rods and hope that it doesnt come back....

[mrennie]

Just thought that I would update, the bumpy wheel is gone after boosting my animation frames first to 600 - on a suggestion from the guys at UKTS. I have since narrowed the frames down to 60 and still have a nice even rotation without a strange bump at the 180 degree mark.
I will now be able to press on with the rods and hope that it doesnt come back....

That's good news. I was going to suggest that you send me that simple cylinder so I could test and see if it happens to me. Animating 40 frames per rotation is a lot of hard work - 60 is going to be even harder.

[savv_nz]

Yes, 60 frames is going to be an animation nightmare, thanks to the wonders of baker valve gear I have 11 rods to animate... per side since its quartered. Never mind, a long slow animation process is better than weird glitches at the half way point.

[mrennie]

Yes, 60 frames is going to be an animation nightmare, thanks to the wonders of baker valve gear I have 11 rods to animate... per side since its quartered. Never mind, a long slow animation process is better than weird glitches at the half way point.

Before you start that, make sure you follow the last tip in my blog - it's absolutely vital!

"Well, almost! There was still a bit of bumpiness for an entirely different reason. What I discovered is that sometimes when trying to position the animation step for something long, such as a siderod, the end of the rod just wouldn't stay where I put it. It happened when the rod was meant to be very close to, but not completely, horizontal. As soon as I let go of the mouse button, it would move by itself until the rod was fully horizontal (and not where it was intended to be). I am absolutely certain that it's a problem of rounding of floating point numbers in some calculations done by 3DC. The solution turned out to be quite simple (but took me months to stumble across). When I have something long to animate, like siderods, I now shift the object within its own group until there is a large angle (close to 45 degrees) between the group axis and the longitudinal axis of the rod. You can see this when you click on the group (rather than the part) and see the group's bounding box. When the group axis is aligned with the part's own axis, the bounding box is very narrow, and that's what causes the problem. Shift the part in the group, to get that 45 degree angle, and the bounding box will be much fatter, which solves the problem."

Good luck with the animation!

[savv_nz]

Hi Mike, yes I had seen that bit - it would explain why no matter what I attempted in other models I continued to have a slight bump at the rod end. I had noticed while doing a test animation yesterday that it seemed to be snapping to a grid of some description when at the near horizontal (a lot more noticeable in this model with its longer rods than the others with their shorter rods).

One more question... do *all* of the rods have to be a child of main, ie would making the connecting rod a child of the coupling rod cause issue if neither of them are children of the wheel - maybe I will just experiment a little. It would make for a lot less time animating if at least some of the rods can be made to be children of other rods...

[mrennie]

ScreenShot001.jpg

Hi Mike, yes I had seen that bit - it would explain why no matter what I attempted in other models I continued to have a slight bump at the rod end. I had noticed while doing a test animation yesterday that it seemed to be snapping to a grid of some description when at the near horizontal (a lot more noticeable in this model with its longer rods than the others with their shorter rods).

One more question... do *all* of the rods have to be a child of main, ie would making the connecting rod a child of the coupling rod cause issue if neither of them are children of the wheel - maybe I will just experiment a little. It would make for a lot less time animating if at least some of the rods can be made to be children of other rods...

My guess is that the snapping to the "grid" at the near horizontal, for long rods, is probably caused by some floating point calculations of very small angles (offsets from the angle of the group axis) that get rounded off. That's why I experimented with changing the orientation of the group axis to increase the angles.

I had a lot of problems when trying to make hierarchies of animated parts (the theory, of course, is that doing so makes it easier to animate parts that are connected), so now I keep them all at the same level in the hierarchy. They don't have to be right at the top, as direct children of the main model ("locomotive", i always call it). Here's how I have the hierarchy set up for the FEF-3:

ScreenShot001.jpg

ScreenShot002.jpg

Another tip is to split the 3DC screen into several windows so that you can see both ends of long rods at the same time, zoomed in for accuracy in positioning them.

One more thing is that for some parts, it's better to put the group centre in the exact centre of one of the hubs (the main rods, for example), because it makes it easier to position them when doing the animation, but in that case, you get another problem which is the thing about the viewing bubble that makes long narrow parts disappear at certain viewing angles. The solution to that is to make a little triangular face and texture it to make it totally transparent, then position it at the roughly the same distance from the group centre as the extreme end of the rod, but in completely the opposite direction. Then merge the triangle into the rod. That way, the group centre is still at one end of the visible rod, but is actually in the middle of the part.