using photogrammetry and megascans to plant a forest

Alex Patel gives us a breakdown on how he used Photogrammetry to create the Plantation scene.

Introduction

Hi everyone! I'm from the UK and have worked on a number of freelance projects over the years. I got hooked on CG Art in general after seeing concept art on the internet like 5 years ago, I saw all the paintings and it was the first time I had been exposed to this kind of stuff and realized this is something I wanted to get into. I'm self taught....Or youtube taught haha!

Inspiration for Photogrammetry

Building the Plantation project was a learning experience for me. This was my first time creating a forest scene... I knew from the outset I wanted to use photogrammetry and megascans to achieve a hyper-real final result. I was really thinking to get it to that level that if you were transported into this place in some kind of Life Simulator, you wouldn’t be able to recognize that it wasn't real life.

Also being a beta tester for AI Texture Creation Software: Artomatix, meant that I was eager to use this software in a project to see how it held up (amazing!).

In terms of building the environment, I knew from the outset i wanted to use a couple of programs and ideas.

SpeedTree is a program I'm very experienced in, and as a result it was my go-to for creating the assets.

I knew I wanted to use the Foliage tool in UE4, as having used it previously I saw the potential to quickly make natural scenes using this technique.

I also knew that minimizing overdraw was a key facet of making a believable forest environment, heres a pic showing the minimal cost with correctly setup foliage.

Photogrammetry Equipment, Software and Workflow

I use a DSLR Camera (Canon 5DSR), tripods (sometimes), Polarizing filters, Phones etc.
For Software I use Reality Capture, but have used Agisoft extensively in the past. Either program is fine, each has their pros and cons.

Photogrammetry is essentially a way to mathematically understand the relationship of objects in space. I't’s really interesting. By comparing the difference in pixels over several photos you can work out the 3D coordinates of pixels and recreate an object in 3D.

For me, Photogrammetry is best used for Rocks/Terrain/Large Outcrops etc. Its spectacular at capturing these incredibly complex and hard to replicate features of our Beautiful Natural World. Its also pretty good at capturing materials, which you can then tile in a program like Artomatix.

However, it struggles with capturing highly reflective objects. There are ways around this (you can buy a spray to dull reflections etc.) But it’s not always convenient or possible to use.

I think for people just starting with photogrammetry, using your phone to take pictures is 100% fine. Then when you get more experience and want to take it to the next level, there are tonnes of great DSLR cameras out there that you can get for quite cheap. Photogrammetry does require some knowledge of cameras, so do some research into Photography concepts such as lighting/sensors/lenses/frames etc.

Creating clean scans is in my opinion, down to a high level understanding of cameras, (understanding how to get the sharpest images/color correction & lighting.) And also down to shooting technique (making sure you get full coverage and the highest detail possible). Then processing the images in a way to get the best result (using RAW images etc).

Scanning Plants is actually a different technique known as Photometry. Also very fun. Essentially, you light the object from 4 directions and take photos and then combine this in programs such as Substance Designer or Artomatix to create the normals of the object. Once you have an atlas of your leaves you can create the plant as normal.