Hi,
as you probably gathered from the title, I am trying to render a photorealistic hourglass (animated as well).
Any ideas on what to improve are welcome for both the image or animation.
If anyone wanted to know each frame took about 2 minutes, as I only rendered the portion with the glass as transparent png and then overlaid it over the image in post.
thanks
sand could have a better material. looks more like brown sugar
A couple of things that comes immediately to my mind are:
1.-The sand is too uniformly gathered at the top side of the hourglass. Im sure you were using this picture as a reference https://upload.wikimedia.org/wikipedia/commons/7/70/Wooden_hourglass_3.jpg, and you can notice that the sand at the top part makes a minor slope. When trying to do realism, subtle aspects like this one are the ones that separates CGI from Realism.
2.-Flat texture. Your main texture is fine, but it is flat regarding its color. When looking at the reference, you can see that the texture becomes darker when it comes closer to some edges. This can be replicated by 3 different methods:
-Dirt paint. It involves vertex color paint. Easy and cheap. (Several tutorials for this available at youtube)
-Ambient Occlusion baking. Just naming it for you to know it’s existance. It can be useful for other things in the future.For this project,It is not the best approach though.
-Pointiness Value Node. Actually, this imitates the way you would use Dirt Paint for this task, but it is way more faster, and real time. I googled a quick tutorial https://www.youtube.com/watch?v=SYslucCSnPI
With pointiness Value node you can imitate the way Wood becomes darker, burnt, at edges. This would increase the realism in your shader by a whole lot.
3.- Im not sure, but I think Im seeing seams on the texture. It is very noticeable at the left pilar, top part. You should fix that, because CG artists see these kinds of things really fast, compared to regular people.
4.-Fresnel input. It is something really hard to get a grasp about how to use it, and why and how it helps for 3D realism. But you definitely should take a look about this.
Some cool tutorials about this:
https://vimeo.com/103108876 .Layer weight has been the way most Blender artists have been imitating Fresnel. Some like to use the Facing input, while others, like in this video, are using the Fresnel input.
https://www.youtube.com/watch?v=pNiVB7tRG68 . CynicatPro is a Blender Artist that makes really good, informative tutorials about realistic materials. He explains fresnel in an awesome way, but he also makes difficult shaders (but shares them) in order to get more realism. Take a look at him after you finished your main, latest project. It will test your knowledge about shaders, even probably your faith (?).
Hell, Im sorry if I suddenly gave you too much information.
Last words: I would fill in a little more the blank spaces. Add some interesting shapes, like little pyramids, or cubes gathered… Add a texture to the wall.
Your lighting seems really good for me. I like the reflection. The post process with ambient particles, fuck yeah. I would love to learn how did you make it or what kind of footage you used.
Cheers!
PS: man I wrote too much, sorry!
Wow, thank you for taking the time to write all that, I really appreciate it.
Yup, that’s my reference 
and I am kind of ashamed that I didn’t even notice the coloring effect, I will surely replicate that
Great point about the uniformity of the sand, thank you.
Emberassingly, you are indeed seeing a UV seam, unfortunately I noticed halfway there and was lazy re-render and thought to myself “no one will notice.” You proved me wrong. I will fix that.
I was actually using fresnel, which is all the more infuriating that it did not show.
The dust particles are really nothing special. Downloaded from here
I will add some things, probably even a little camera motion and some meaning to the video to make it less boring, I just wanted to get the hourglass right first.
Thank you so much for all you wrote, you really helped a lot 
Well, getting fresnel to look “correctly” is actually really difficult in blender, because it isnt that accurate. And it is also a very subtle thing so sometimes if someone cant notice it, dont bother too much about it.
It is cool that you took my advices this lightheartedly (is that a word?:P). About seams, yeah, you can never leave those things pointing at the camera, CG artists always see these kind of things almost instantly. It is the same as gamers can notice the difference (and get annoyed by) between 60 fps and 30 fps, while normal people are like…“wtf?”. We just see and explore with our vision at a different level.
If you have that much time, go nuts with your work. I would just recommend taking the fastest route to finish it though, so you can start another project and exploring new nodes like the Pointiness Value. It is really fun to use it.
Glad I was helpful.
Cheers!
ps: thanks for the link!
It looks very nice. For purposes of realism though, my suggestion would be to add a slight tilt or unevenness to the top of the sand in the upper bulb. Turning over a sand hourglass rarely leaves it perfectly flat like that.
This is very well done, well above anything I am able to do. One thing I noticed though is that the glass seems to intersect the posts. It almost looks like that messes with the lighting on the one seen behind the glass in the center. Possibly you could use a Boolean to cut out that section off the posts, or slightly scale down the glass.
There also seems to be a gap between the bottom edge of the posts and the base, though that may be intentional.
Thank you all for the ideas.
The gap is intentional, but the intersection definitely not and well spoted indeed. Thank you.
Stellar work! I agree with Gmodder that this surpasses my ability 
Nevertheless,
Perhaps adding a bit more perspective to the camera would improve this…I think it looks a bit too orthographic. Also try some more post effects: bloom, vignette, DOF.
Nice work!
I think you did a great job with this! I like the subtle dust particles a lot, because I’ve been trying to figure out how to make those realistic.
Again, thank you all.
Oxter Brothers - regarding the dust, it was just faked in post… I talked about it somewhere above. Someone might say it’s cheating a bit, but I feel it’s much easier and faster usually then going with some particle setup. It would only work for still camera however.
It is never cheating when you get the job done.
You would think everything you see in CGI movies is done in 3D, while most of the time backgrounds are just mate paints. There is plenty of it.
That is just a minor example, but I hope you get my point.
