This article, written by Paul Parneix, was originally posted on Poulp.io.
This tutorial will guide you step by step in the process of creating a photorealistic PBR sourdough bread 3D material.
Part 1: Making the Bread
Ok, I just lied, this is actually about a (still kind of procedural) bread recipe!
During this weird COVID19 lockdown situation, it seems that a lot of people are baking homemade bread, So let’s be super original and try that! (I heard that Frenchies are quite good at it) 😉
Making bread is not that easy and I’m far from being an expert, but it’s really satisfying when you end up with a good result. I learned a bit about the fermentation process during my time at Biology University, and it’s fascinating.
Prepare Sourdough Starter
Sourdough is a naturally fermented mix of water and flour. Before the discovery of baker’s yeast, Sourdough was the only way to make bread.
So yeah, using sourdough is the vintage/hipster way of making bread! Sourdough loaves are characterized by intricately scored brownish crusts and nice holey crumbs. They also develop a typical light sour taste, more complex flavor and you can keep them fresh way longer.
Growing a mature sourdough takes approximately one week.
The idea is to mix flour and water and let the natural microbiological flora of the flour grows up. In the beginning, there will be a very heterogeneous population of microorganisms. Natural selection will happen and your mature sourdough should contain a mix of lactic acid bacteria and yeasts living in symbiosis.
Sourdough Starter Recipe
Day one: mix 20g of flour with 20g of tepid water in a glass jar. You can add a bit of honey to give it a sugar boost, but it’s not mandatory. Prefer mineral or filtered water and organic flour (rye flour works well to start a sourdough), you want to avoid any kind of chlorine/antifungal to make sure natural bacteria & yeasts will grow well.
Cover the jar but make sure air can still pass, and leave at room temperature.
Day two: add 40g of flour with 40g of tepid water and mix. Cover (make sure air can still pass) and leave at room temperature.
Day three: If you started with rye flour, you can now switch to wheat floor. Add 80g of flour with 80g of tepid water and mix. cover (make sure air can still pass) and leave at room temperature.
Next days: Keep the same logic, for a sourdough mass m, add m * 2 flour and m * 2 water and mix. It’s important to start small or you’ll end up with a ton of sourdough by the end of the week!
My sourdough starter after two weeks.
You should start seeing bubbles around day 3/4, and after approximately one week, end up with a nice bubbly and living sourdough. You know it’s good to use when it almost double in volume 2-3 hours after feeding it.
Don’t be afraid of the vinegar/beer/malt smell, it’s perfectly fine. Keep in mind it’s a living ecosystem so you need to feed it ~ every day a room temp, or once a week if you keep it in the fridge. You can keep it for years as long as you feed it to keep it alive.
For a generous old school loaf, you’ll need:
- 500g of strong (T65) wheat flour. You can also use 400g of wheat flour and 100g of another flour, for this one I used wheat and buckwheat flours.
- 200g of sourdough starter.
- 300-350g of tepid water.
- 10g of sea salt.
The quantity of water depends on the protein level of your wheat, the best thing is to try and adjust next time.
1. Mix the Ingredients
Mix flour(s) and water and salt in a glass bow using you hands or a spoon.
Then add the sourdough starter and mix again.
After a rough mix in the bowl, you can put the dough on a lightly floured table, and start the manual kneading. (Don’t add too much flour even if the dough sticks a bit, you want to keep a good hydration level)
Kneading is about developing gluten structures in the dough by stretching it (without breaking it) to give it its “elastic” property that will keep the gas inside during fermentation, and produce a light crumb.
The dough before and after kneading
It can take from 10 to 30 minutes depending on a lot of factors, you know you’re good when you can stretch the dough and see a thin membrane without breaking it.
Thin membrane structured by gluten
Place the dough in a glass bowl and cover it with a wet towel.
Let it prove for ~three hours at room temperature. it should almost double in size.
Gently take the dough out of the bowl, and place it on a floured table. flatten it a little bit (be careful, and try to keep the gas inside the dough). Shape a round “ball” by grabbing the exteriors and pulling them to the center.
For this one, I wanted to try a flat like old school “tourte” bread, so shaping was pretty simple and loose.
A last proofing step is required before baking.
Place the dough in some shaping basket/banneton. If like me you don’t have one, you can use any kind of bowl covered with a towel topped with a lot of flour.
Let it prove for another three hours at room temperature.
If you dent the dough with your finger, and it tries to snap back to its original position very slowly, it’s ready to bake! If it doesn’t snap at all, it’s probably too late, and if it snaps back quite fast, let it proof a bit more.
Finally, the dough is ready for baking! Bread needs some good high temperatures, so preheat your oven up to 250 °C.
Place the dough on a baking plate (by flipping the shaping basket upside down) and score your bread using a baker lame/razor blade. this signature is not only pretty, but it also helps to give a direction for the gas to go out of the dough, to control the crumb structure and final shape.
Bread also need steam to develop a nice crust, place another baking plate in your oven, and throw some hot water into it just before putting the bread plate in.
Bake 15 min a 250 °C, and ~10 additional minutes a 230 °C. Might vary depending on the bread shape or oven, it’s better to monitor carefully the last 10 minutes.
Let it cool at least ~one hour before opening it. You can also keep it multiple days as it is because sourdough bread lasts longer than industrial yeast ones.
Part 2: 3D Scanning
To keep things a bit on topic here, lets 3D scan that loaf.
Sadly, I don’t have my Softbox Surface Scanner with me, but I still have a decent DSLR and a polarized ring flash! I shot a set of cross & parallel polarized pictures of the bread
Some cross-polarized pictures used for the scan
After a quick reconstruction in Reality Capture, I ended up with this nice highpoly model:
Quick photogrammetry scan preview
I created a low poly 3D plane with UV’s matching the surface of the bread for baking (the maps, not the bread 🙂 )
Tiled PBR maps extracted after baking, respectively Albedo, Normals, Height and Roughness.
Roughness was guessed by subtracting cross-polarized texture (albedo) from the parallel-polarized one. Not super accurate but better than nothing. I used Substance Designer for final roughness and other maps tweaking.
Tweaking in Substance Designer
Just for fun, I started Substance Painter, and did a quick projection of the above maps on MeetMat model! The crumb on the right is just a quick & dirty Bitmap2Material.
Closeup on the arm.
A #BakedGoodsChallenge challenge just started on Sketchfab. I’ll try to do a proper scan (not just for texture) before May 15.
Thanks for reading, I promise this place will not become a cooking blog 🙂 By the way, reproducing complex bread crusts fully procedurally in Substance Designer would also be super interesting.
Change the random seed, and repeat the process !
Another bread scored with a single vertical line