Moving water in a sewage pipe

I have drawn a sewage pipe… What would like te have is a animation where the pipe fills up to half and then drains again…
I also would like to use like vray for better images…

Can anyone help me ?.

Create a series of scenes depicting the steps in the sequence and play them as an animation. This is a basic function of scenes. Read this:

Animating Sections and Scenes

(Are you planning to show the pipe in section? How will the viewer see what’s inside the pipe?)


I already made scenes and i also used section plane… even a section plane in a group…
I think to problem with section plane is it does’t see a solid as a real solid…

If you try to saw wood alhf way you still see wood… But with sector plane even a box is hollow inside…

When i am using “section plane”





Last one… Problem is that only both end are moving up and in the rest of the pipe you can not see the water anymore.

@MarkS1, you seem to be all over the place. You certainly might have mentioned in your original post that you had already tried using scenes, although it isn’t clear what your actual problem is, or which problem you want help with, or, for that matter, what kind of help you’re looking for.

First of all, you have to readjust your expectations. SU is a surface modeler. By their nature, all SU models are “hollow.” If you want the appearance of a face to suggest that you have exposed a “solid” inside with a cut, you have to put it there.

Now, as far as your simulation of rising water, who even knows how you did it? It would be hard to agree that there’s a problem with SU when it’s equally likely (or more likely) that something you’re doing or not doing is at fault. The fact is, in your last screen shot, I see what appears to be muddy (or otherwise contaminated) water standing in the pipe. It’s too dark and too transparent to be very visible, but I presume the color and transparency are as you set them.

Let’s try to address your problem(s) systematically. Try to be very clear about what your first problem is, recognizing the difference between you doing something wrong and the program doing something wrong, and try to solve that. Then let’s move to your next problem, and so on.


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Seems to me that the simple fix would be to model the water volume (with a visible top surface) to conform to the cylindrical shape of the pipe having the various scenes adjusted to show the changing level of the water.

SU models surfaces: when you cut a surface of a “solid” with a cuting plane, you are seeing the inside of it:

So to do what you want, you need to make the “Liquid” a solid object that is a fraction off touching the edge of the pipe (if you hid the pipe, you would still see the liquid conforming to the shape of the pipe and not just the top surface.)

You now apply scenes with cutting planes inside the liquid group and it will look like the liquid is rising/falling. (You may also want to change the style to remove the thickness of the cutting plane lines)

Hi Mark

Is this the sort of animation you are after with the rise and fall of the water/liquid?


Wow how did you make this animation @Fruntside ? :open_mouth: There’s no Z-fighting and your section plane doesn’t erase the top surface. I tried replicating it but it’s not the same. I’m scratching my head here. Good job!

@VahePaulman - Thanks for the kind words.

I haven’t used section planes for this particular application for the very reason that you have mentioned, it erases the top surface. Section planes are great for so many jobs, but not the right tool for this one.

I used Keyframe Animation, which uses the scenes as keyframes (which essentially that is all they are anyways). Generally, you would use this plugin to move components and subcomponents around your model and save their location at each of the keyframes. Playing back will move the components around. Great for making various animations. One other function of the plugin is that it lets you scale the components and save the new size of the component for each scene. In this case the liquid inside the pipe has been scaled down and saved at each Keyframe. You can then play the animation within SketchUp or export as an animation.

To combat the Z-Fighting, I simply dropped the water component on the vertical axis by .01 of a mm so the two planes aren’t fighting for the same space.

@MarkS1 – Here is some examples of the rendered liquid you mentioned in your original post. Also all done in Sketchup. Pretty quick render, but still looks quite cool with the reflections and refractions.

Hope this helps, Fruntside

Clear Liquid

Blue Liquid

Red Liquid


Without using any pugins or keyframe animations: the attached is just doing what I said in my previous post…

Filling up.skp (181.6 KB)

Hi @gadget. Sorry, I can’t open your attached file to view, but judging by your screenshot it looks like the section plane has chopped the top off, and yes I agree that you mentioned this in your previous post.

To be fair, you could also make the animation I have made in my above post without out any plugins and keyframe animation. To make it with the same level degree of smoothness. You would have to divide each scene into 26 scenes (26 frames per second, if you were assuming that each original scene was a second long, similar to my above example). Then for every scene you would need to create a new water component and scale it down incrementally smaller than the last. Using your layers and scenes, you then need to turn on and off the visibility of the water component for each of these scenes and save the scene accordingly. Each of the new scenes would need to be set to the duration of about 0.03 seconds in the animation settings to represent one frame.

No one would ever have the time or patience to actually do this, however it is achievable. The plugin I have used, dose exactly what I have outlined above, it just automates and streamlines the process, so what would take you hours to do manually, is done in matters of minutes.

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The look of the cut plane section is intentional: it only has to look like the water is rising and falling - the only disadvantage of using this method is that you don’t actually have a surface; it just looks like you do*. I used the same method a while ago for filling up foundations (just need to hide the ‘inside’ lines).

This way is quicker, the file size is much smaller and you don’t need any plugins. You could also have the liquid flowing down the pipe if you tilted the second cut plane. (I would also make the fill about 30% opaque)… Filling up.skp (191.5 KB) {Edit: oops - same one… changed now}

(*no surface means that any rendering won’t work… but I’m not sure that cut sections export out to render packages anyway)

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Thanx … this is what i need… can i have your model, so i can try to remake it and learn in the process…