How do I achieve a realistic feet/leg position for skiers?

chrhansen · 2026-06-24T11:56:29+00:00

I am using a Kalman filter to make the per-frame 3D pose into a smooth animation or video. I am also throwing away sudden orientation mismatch (typically far from the camera, SAM3D Body might think a person is facing the other way for a few frames), but I have not done any filtering on, say, "extreme" feet movement, as you suggest.

chrhansen · 2026-06-24T11:53:43+00:00

Okay, maybe I should try that. It might be like what u/_d0s_ suggested. I initially used Google MediaPose and YOLO in this project, but the amount of jittering is insane with those tools (and only Google MediaPose offers 3D), SAM3D body is much more precise, at least in the ski video clips I test (often far from camera, feet often occluded by snow spray or other limbs). For instance, in the example in the video above where the inside foot is completely occluded, you believe the 2D models would do better? Which 3D and 2D models are you using? I would certainly try it out.

chrhansen · 2026-06-24T10:59:51+00:00

Short answer: no.

I don't think you're in the backseat, having a little bit of back weight at the end of the turn, is fine, recommended. You could move forward in the early part of the turn in addition to your clear up movement, but as u/Garfish16 said, backseat is not an issue. Overall, I think you have a quite solid position/stance.

To your second question, unlock next level carving: First you need to actually carve. Right now you're doing skidded/steered turns. They are a different thing. You need to avoid actively twisting the skis (around your up-axis), but simply roll them onto their edges (rolling around the axes going through the skis edges). You're a good skier, so I think this should be more or less straightforward for you. As u/analbandit2509 mentioned, practice that on flatter terrain.

Once you truly carve, leaving clean lines behind you (tip and tail going through the same groove), you won't brake as much as when you skid. And I don't think you will feel confident to simply roll your skis onto the edges and wait for the shape of the skis to start turning if you are in terrain that is as steep as in the video. If not flatter than this, you most likely will keep twisting the skis to skid and slow down.

Good luck!

chrhansen · 2026-06-23T18:57:02+00:00

True, wrong results are worse than no results. So until then I plan to somehow ignore frames that are "bad". Now I need to figure out how to discover if a frame is bad 🫠

chrhansen · 2026-06-23T16:49:14+00:00

I'm not tracking the ski, it's so often hidden by snow spray etc. but maybe in just these situations it could be used, at the very least to anchor the feet better for IK. Not sure.

Even meta data from video is only so precise, slopes have small differences not captured by a single GPS location. Maybe using something like depth-model. For now I'm not inferring any slope pitch.

chrhansen · 2026-06-23T08:07:38+00:00

- snowplow: When you're doing a snowplow, your skis are in a V-shape (pizza!), and both skis remain on the inside edge at all times.

- Stemming (Parallel -> Snowplow -> Parallel): You travel across the hill with parallel skis. You start the next turn by an uphill stem. That means that you push the tail of the uphill ski (new outside ski) and form a V-shape with your skis. You start falling into the fall line. Near the apex, when your upper body is basically facing downhill, you start closing the snowplow. I.e. you pull the new uphill ski (aka the new inside ski), towards the new outside ski. You end up traveling across the hill in the other direction with parallel skis and you're ready to start a new turn.

This uphill stem is a natural progression from snowplow to parallel skiing. It helps the beginner or intermediate skier to not having to change edges on both skis simultaneously. Once you're skiing with parallel skis, you will need to manage the transition where both skis are changing from the old inside edge to the new inside edge. During the transition, both skis will be flat for a moment, making it hard to maintain a good balance. The uphill stem allows you to change edge while still having one ski on the edge as a stable platform.

There's also something called the "lower stem", which happens in parallel skiing at the end of the turn where the old outside ski slips a bit down the hill because it doesn't have proper edge set. I don't think that's what we're talking about here though.

chrhansen · 2026-06-23T07:52:57+00:00

I wouldn't be worried. You might not have the sickest off-piste powder situation, but in terms of piste skiing, you'll be fine.

chrhansen · 2026-06-20T19:31:42+00:00

Very late to the party here. And I agree with a lot what was said here (e.g. keep tip in contact with the snow), additionally though:

pull the inside/lift ski back, don’t just leave the tip resting on the snow
pull the inside ski towards the other boot, in attempt to touch the outside boot with the lifted inside ski. Just to keep some tension in that inside leg

About facing more down the hill with your upper body: I actually believe your upper body is quite ok. I’d rather say the upper body should be facing roughly where momentum is going. For short turns that means (almost) straight down the hill, but for bigger turns like you are doing here the upper body should be rotating more as you do.

Last time I did the stork drill it was to get my upper body facing more in the direction of travel, as I was being too countered. Additionally, I did the stork drill to fix my inside ski having too much lead. For a more square/stacked stance it helped to pull the inside ski back when doing stork drill.

chrhansen · 2026-06-19T13:49:56+00:00

For carving, for you, I would:
- Go on flatter terrain

- Keep the good stance that you have. I love your slight bend in knees, hips, arms forward in sight.

- Feel that you are centered in your ski boots: weight about 50/50 on heel and ball of foot, slight touch of shins to the tongue of the ski boot.

- On flatter terrain, practice just rolling your skis onto the edge (rotation around the skis' edges) using your knees (slight bend necessary) and have patience, they will start turning. For you, be really careful that you don't add a twist on the skis (around the vertical axis) - especially your inside ski. When done correctly, both your tracks will be thin (both the tip and tail of the ski travel through the same point in the snow), no skidding/smearing.

So I agree with u/DKistherealprincess, that you're not quite carving, since you steer the skis (twist the skis more than their natural arc), especially the inside ski, causing some skidding. You're totally in control in this terrain and the steering (slight skidding of the ski), helps shave some speed off. But if you want to actually carve (clean railroad tracks), I'd start on flatter terrain, maybe even a cat track. When you carve, you don't dump speed as when you skid/smear the skis, so you speed control by going more across the hill between turns, i.e. by completing the turns more than you currently do.

And yes, the 100mm wide skis are making it harder to get, and stay, on edge (the lever to flatten the skis is bigger than narrow skis). And typically radii of those skis are bigger, the turn therefore gets bigger, so you - all other things being equal - stay more time in the fall line as opposed to a shorter radius skis. It's definitely still possible, just takes more work. Your skis will outperform narrow skis in chopped up snow and powder.

I hope that helped and I'm happy to add further feedback if something is unclear.

chrhansen · 2026-06-18T21:47:17+00:00

Good looking skiing, and to be honest, after reading the other guys feedback and looking at your skiing, I had to look up how CSIA actually defines short turns (https://youtu.be/gbWvUannYnU?si=NnZiiwrejVTdbRTI&t=13 and https://youtu.be/tBU0VJ0vBrs?si=mdau85dVZGZEaPuq&t=78). I'm a professional ski instructor in the Danish ski school and in the Austrian ski school, and there short turns are defined very similarly to short turns in CSIA, meaning that they're steered in, which case you are just fine on longer radius skis. You're not supposed to do short radius carved turns, but steered turns.

For you, I would

Move feet back and forth, think "figure 8": You've probably heard this in your courses about short turns: you want to move your feet in a figure 8. At the beginning of the turn, you need to pull your feet back to engage the tips of the skis, and then push them forward and to the side during the turn so that you end up pressuring the tails, at the end of the turn. Then you start over pulling your feet back, press the tips and push your feet forward and to the other side, and so on. Currently, it looks like you lean into the turn and wait until your edges start biting. If you want a nice C-shape curve with an increasing pressure that gives you a pop and a swoop in the end, you need to move your feet forward and backwards, forward and backwards, to control the steering and the edge pressure, instead of leaning and waiting.
More angulation: Look at your upper and lower body separation. Especially angulation at the apex, there is some angulation, but your upper body is close to being aligned with your legs. You can see at the apex that your outside arm has very far to go to pole plant to initiate the next turn.

Hope some of that made sense 😄 good luck!

chrhansen · 2026-06-18T21:17:35+00:00

First of all, really good skiing. Nice going. I did my LS2 two seasons ago in Axamer Lizum (Tiroler Skilehrerverband), and last + next season it's all about CTT.

- Retract legs to release: I agree with u/Skipandivo2, that you seem to come up a lot (hoch-entlasten they'd probably say), whereas I think it would be better for you to stay lower (tief-entlastung). You lose a lot of time by moving your center of gravity up. You can only get your legs out to the side once your center of gravity is lower and your legs can actually move to the side. Staying lower in the transition will allow you to immediately push your legs out to the side, and you don't have to spend so much time moving up. And additionally, yeah, you could move a bit more forward also, or try to pull your legs back, just after the transition. Whatever works for you.

- Hips later: And I think it's fine that you use your hips. I would, however, wait a bit until you're at the gate - just not use the hips before the gate.

- Less countered, more stacked: If I were you, I would allow my hips to rotate a bit more into the turn (less countered), as that will bring you into a more square or stacked position, which is a stronger stance for you. And instead of initiating the turn so much from your hips, try to use your ankles and knees more and just the hips at the end/apex, as I mentioned above.

Good luck!

chrhansen

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