importing a stepped image sequence, ignore missing frames?

In case you are still looking for an answer, I think this is what you might be looking for:

When importing your images, select 'importerJPEG Sequence' and 'Force Alphabetical Order'. AE will now ignore the missing images. In the 'Interpret footage' options set the assume frame rate to how many images you have in 1 sec. So your frame rate should be 30 fps and you have 3 images that should last 10 frames each set it to 3 fps. AE will now make the images last 10 frames and you will have the original 30 fps back with 3 images lasting 10 frames each.

Hope this helps!

Thanks for the solutions.

It seems there isn't an easy/quick solution to this, so I've managed to solve it within the 3D software by adjusting the framerate temporarily rather than the stepped frame output.

If your image sequence has missing frames and maintaining the time difference between frames is critical you need to use some scripting or other techniques to rename the images or insert placeholders to fix the missing images. If the time between frames is not critical then there is no problem showing every 10th frame. As long as you don't need to delete the extra frames to save space the solution only requires a couple of clicks of your mouse. Let me explain.

Your comp is 24 fps. You have a video or image sequence that is 24 fps and it's 10 minutes long. Drop the source footage into a 24 fps composition and it takes 10 seconds to playback and you see every frame. There is no frame blending or skipping.

Select the footage (or image sequence) in the Project Panel and use the File menu or Right-click to change interpolation to 240 fps and the footage will now playback in 1 second instead of 10. Drop it in a 24 fps comp and you will see every tenth frame. There is no need for frame blending because the frame rates are evenly divisible. Change the frame rate interpolation to 120 fps and the clip now plays back in 2 seconds and you see every 5th frame. All you have to do is do the math.

If the frame rate of the comp is not evenly divisible by the frame rate of the footage, you will get some frame blending. Make the frame rate of the footage less than the frame rate of the comp and you will get some frame blending. On its own After Effects does a very good job of blending frames. If you need to do some crazy slowdown then Twixtor Pro does an even better job, an amazing job really, of predicting where the pixels are going to move and giving you amazing slow motion from normal frame rate footage. If you are going the other way, speeding things up, and you don't need to add motion blur, all you have to do is evenly divide the frame rate.

Because After Effects does not change the original source files, the project size and the rendering time will not change if you change the interpreted frame rate of any kind of footage.

I hope this helps. I change the frame rates of my source footage all the time. I also force motion blur all the time when I speed things up. I always shoot at high shutter speeds when I need to rotoscope or greenscreen to reduce motion blur, then put it back in after the matte is created so I get better results. These are all good "tricks of the trade" that you should learn.

You can select every 10th frame of your image sequence in Explorer/Finder (Python will come in handy here if you have to do it a lot) and isolet them. Then you can rename them using Advances Renamer to make them a continously sequence again (1,2,3 ...).

This new image sequence goes into AE, where you set the fps to a 10th of the fps of the original image sequence.

*Martin