Sandbag modelling ?

Question

Hey there guys, just after some tips to model or sculpt a wall of sandbags realistically (ie not looking like a bunch of pillows). Especially where there’s creases pinching at the tied off area, and how to model the tied off area itself. Polycount isn’t a massive issue, as this will be for 3d resin printing.

Also how would you go around making the wall itself to make sure the sandbags look realistic in the sense that they sag a little and also easily follow a certain shape (eg like the curved wall below?)

sandbag.jpg

Thanks in advance.

  • Adrian Bellworthy replied

    Hey rfranks,
    For the curved wall, this is achieved with placement of each sandbag, not the sandbag being curved.
    Which brings us to the modeling,
    1, you could model 3 or 4 variations of sandbag, duplicate and place them to build up the wall, or
    2, you could model the wall as a single object, sculpting the shape of individual sandbags.
    I personally would go with 1.
    When sculpting the tied up end, you could use the crease brush to make these, with plenty of time and patients.
    Although not all sandbags have a tied up end, military sandbags are often sewn closed for transport and re-use.
    sandbag.jpg

  • Martin Bergwerf replied

    Hi Ross,

    I do not know of an easy way to do this. Adrian already gave some great advice!

    What you could also try, is to make a Softbody Object for the sand filling and a Cloth around that for the actual bag. (Do that a few times to get different bags.) There are some Setting in the Cloth Physics that can help, test the Shrinking factor...Also, you can make a Shapekey for some Vertices to tie up the bag, this works pretty well together with the Cloth (use Pinning for that Vertex Group), but will require some testing to get the result you want...The rope, used to tie them needs to be modeled separately.

    I used this technique to make a garbage bag. See:

    https://cgcookie.mavenseed.com/community/7738-30-days-of-modeling?page=14

    Making a wall out of them is going to be a lot of extra work!

    You will probably want to remove the 'sand' Objects when you are ready, before printing.

  • Omar Domenech replied

    Well, I bet there are techniques with simulations that could get you to achieve the sandbag form, but probably you will waste a lot of time tweaking all the settings to end up with fluffy pillow looking sandbags. I say try the sims but don't spend too much time on it, because the real winner I think will be sculpting it. Maybe a mixture of some simulation and then sculpting for the getting it to look just right.

    I think this lessons might help you achieve the wrinkles on the sandbags. It's one of the art of sculpting lessons from Kent. It's an oldie but goodie. It's about the content, not how Blender has changed since then.

    https://cgcookie.mavenseed.com/lessons/clothing