使用摄影测量，ZBrush和Marmoset重新创建雅典娜雕像
本帖最后由 DiGiToTo 于 2022-4-9 00:18 编辑Maxime Marier told us about the workflow behind the Athena project, talked about the right weather conditions for photogrammetry, and explained why Marmoset Toolbag was chosen for rendering.
Maxime Marier向我们讲述了Athena项目背后的工作流程，谈论了摄影测量的正确天气条件，并解释了为什么选择Marmoset Toolbag进行渲染。
Photogrammetry is getting more and more popular, allowing the creation of extremely realistic renders by using photos of real objects. Maxime Marier, a teacher at Isart Digital, Creative School in Video Games & 3D-VFX, has shared the work process behind creating the Athena statue using photogrammetry.
摄影测量学越来越流行，允许通过使用真实物体的照片来创建非常逼真的渲染。Maxime Marier是Isart Digital, Creative School的一名视频游戏和3D-VFX教师，他分享了使用摄影测量法创建雅典娜雕像的工作过程。
Introduction
介绍
One technology I always wanted to try since it came out was photogrammetry, the process to create a 3D model of a real-world object with high-quality pictures. From what I’ve seen, no other techniques achieve the level of realism that this technology can.
自从摄影测量技术问世以来，我一直想尝试的一项技术是摄影测量，这是一种用高质量的图片创建真实世界物体的3D模型的过程。据我所知，没有其他技术能达到这种技术所能达到的现实程度。
The Athena Project
雅典娜项目
One project that made me want to try this technology more than any other is Star Wars: Battlefront. In the new EA version from Dice Studios, they used photogrammetry to make the levels of the games more believable than ever. As you can see in the picture below, they did go to the set of the original Star Wars trilogy to take high-quality pictures of the set. With those pictures, the team at Dice was able to recreate each asset of the set with an incredible amount of detail. It was more than enough to spark interest in that technology in me as a Star Wars fan.
最让我想尝试这种技术的项目是《星球大战:前线》。在Dice Studios的新EA版本中，他们使用了摄影测量技术来让游戏关卡变得更加可信。正如你在下面的图片中看到的，他们确实去了《星球大战》三部曲最初的片场拍摄高质量的照片。借助这些图片，Dice团队能够以令人难以置信的细节重新创造集合中的每个资产。作为一个星球大战的粉丝，这足以激发我对这种技术的兴趣。
The team taking pictures of the Redwoods forest (Grizzly Creek Redwoods State Park) used for the Moon of Endor set in Star Wars: Return of the Jedi.
拍摄红杉森林(灰熊溪红杉州立公园)的团队曾为《星球大战:绝地归来》中的恩多月亮拍摄过照片。
I highly suggest you watch the Dice GDC talk about the photogrammetry process used in Battlefront, it is available on YouTube. Having played the game, I have to say that it does feel like you are right there on the set of the original trilogy.
我强烈建议你去观看Dice GDC关于《Battlefront》中使用的摄影测量过程的演讲，你可以在YouTube上找到它。在玩过这款游戏后，我不得不说，你会觉得自己就像置身于最初三部曲的场景中。
This GDC conference from Dice was a great starting point for me. The first thing I understood is that I needed some high-quality photography. I do have some basic knowledge myself, but I am no photographer. At the time, I was working at Institut Grasset in the 3D Animation department. One of the subjects taught there is TV production and Movie Making, and, as you probably know, mastering a camera is a fundamental part of those classes.
这次来自Dice的GDC大会对我来说是一个很好的起点。我明白的第一件事就是我需要一些高质量的照片。我自己也有一些基本的知识，但我不是摄影师。当时，我在Grasset学院的3D动画部门工作。其中一门课程是电视制作和电影制作，你可能知道，掌握相机是这些课程的基础部分。
So I decided to ask my colleague Jonathan from that department if he wanted to help me to take high-quality pictures of a monument right here in Montreal. Fortunately for me, Jonathan was interested to help me for a few hours of the photoshoot.
所以我决定问我那个部门的同事乔纳森他是否愿意帮我拍一些在蒙特利尔这里的一个纪念碑的高质量的照片。幸运的是，乔纳森很有兴趣帮我拍几个小时的照片。
The Photoshoot
拍摄
The first step of the project was to choose a subject, in that case, a monument or a statue. This website about public art in Montreal was helpful for that task. When browsing the website, I came across a statue of Athena located on Jean-Talon. At first sight, I knew it would be an interesting subject for our photogrammetry project.
这个项目的第一步是选择一个主题，在这种情况下，是一座纪念碑或一座雕像。这个关于蒙特利尔公共艺术的网站对这项任务很有帮助。在浏览网站时，我偶然发现了位于让-塔龙岛上的雅典娜雕像。乍一看，我知道这将是我们摄影测量项目的一个有趣的主题。
So we took a car, a big ladder and professional camera equipment and took off to Athena’s park. Right away I was happy with my choice because it is indeed a beautiful piece of art. It was quite a challenge because the height of the statue is 2.31 meters and getting the full coverage for the pictures was difficult.
所以我们开了一辆车，带了一个大梯子和专业的摄影器材，出发去了雅典娜公园。我很高兴我的选择，因为它确实是一件美丽的艺术品。这是一个相当大的挑战，因为雕像的高度是2.31米，拍摄完整的照片很困难。
The process of shooting a subject for photogrammetry involves taking pictures all around the object to cover 360 degrees from multiple angles. As you can see in the picture below, we took a full 360 of the statue from 3 angles for maximum coverage, we also took some close-up shots for extra details. The blue squares in the image below represent every picture taken during the shoot, the software is able to calculate the position of every picture from the area when you input each individual picture.
为摄影测量拍摄对象的过程包括从多个角度拍摄对象周围360度的照片。正如你在下面的图片中看到的，我们从3个角度拍摄了雕像的360度全景，以获得最大的覆盖范围，我们还拍摄了一些特写镜头以获得额外的细节。下图中的蓝色方块代表拍摄过程中拍摄的每张照片，当您输入每张照片时，软件能够从该区域计算出每张照片的位置。
That makes for a total of 336 pictures and nearly 10GB of raw pictures. Jonathan provided me with compressed JPG and RAW files, for this project I choose RAW for maximum control of the images.
总共有336张图片和近10GB的原始图片。Jonathan为我提供了压缩的JPG和RAW文件，对于这个项目，我选择RAW来最大限度地控制图像。
One thing that was difficult to control in this shoot was the lighting conditions. The shoot itself can take some time, so the lighting conditions will change during the day. The day we did the shoot, it was partly cloudy, and you can see the cloud pattern moving on the statue itself, which is not ideal. I think to have the best results, you need to choose a cloudy day, so the lighting is as diffuse as possible on your object and you don’t have shadows that can impact the result of the photogrammetry. That is for an exterior shoot, of course, if you can bring your subject inside for a real studio shoot, it's the best thing you can do.
在这次拍摄中，有一件事很难控制，那就是灯光条件。拍摄本身可能需要一些时间，所以白天的照明条件会发生变化。我们拍摄的那天，有部分云朵，你可以看到云朵图案在雕像上移动，这并不理想。我认为要得到最好的结果，你需要选择一个阴天，让你拍摄的物体上的光线尽可能的漫反射，而且你不会自身不能有阴影，这会影响摄影测量的结果。当然，这是外景拍摄，如果你能把你的拍摄对象带进真正的工作室拍摄就最好了。
You can see the settings I used for the processing of the raw files in Photoshop, the camera settings are also there. The point of the settings used here is to get the maximum information from the raw files and avoid dark shadows or burned highlights that can lead to a loss of information in the pictures. I exported the final result as uncompressed .tiff files.
你可以看到我在Photoshop中处理原始文件时的设置，相机的设置也在这里。这里使用的设置是为了从原始文件中获取最大的信息，避免可能导致图片信息丢失的阴影或烧焦的高光。我将最终的结果导出为未压缩的.tiff文件。
Generating and Processing the 3D Model
生成和处理三维模型
I ended up testing two softwares for processing the pictures and generating the 3D model: Agisoft Metashape and Reality Capture. The result I had was that the model from Reality Capture seems slightly better than the one from Metashape, but they were really close.
最后，我测试了两款用于处理图片和生成3D模型的软件:Agisoft Metashape和Reality Capture。我得到的结果是，《Reality Capture》中的模型似乎比《metshape》中的模型略好一些，但它们真的很接近。
The main problem I had with the generation of the high-resolution 3D model is that the model generated from the full statue pictures did not have enough details. One simple explanation for that is that when you have the full statue in a picture, there is a loss of space around the statue, too much to be able to fully capture the subject.
我在生成高分辨率3D模型时遇到的主要问题是，从完整的雕像图片中生成的模型没有足够的细节。一个简单的解释是，当你使用图片生成雕像时，雕像周围的空间会丢失，空间会丢失太多以至于无法完全捕捉主体。
What I ended up doing is generating a model from the close-up shot of the head. Once I had the full-size model and the head, I was able to stitch both those models with the ZBrush's DynaMesh. In ZBrush, I also did the final step of cleaning the sculpt with the sculpting tools. As you can see in the final result, I was able to keep the texture data safe by transferring the texture to ZBrush vertex color data.
我最后做的是根据头部的特写生成一个模型。一旦我有了全尺寸的模型和头部，我就可以用ZBrush的DynaMesh缝合这两个模型。在ZBrush中，我还用雕刻工具做了最后一步的清理。正如你在最终结果中看到的，我能够通过将纹理传输到ZBrush顶点颜色数据来保证纹理数据的安全。
Optimization
优化
Now, with the high-resolution model scan of my statue in hand, I know I needed to do some optimization to have a model that works well in a real-time rendering engine. There are some tools for automatic retopology, but I wanted a level of detail those tools could not do, so in the end, I chose to manually make a new topology with Maya's Quad Draw tool. Doing it manually does take a considerate amount of time, 5–6 hours in that case, but I feel the level of detail of the final render was worth it, I also wanted to do justice to the original work.
现在，有了我的雕像的高分辨率模型扫描，我知道我需要做一些优化，以获得一个在实时渲染引擎中能良好工作的模型。我有一些自动拓扑的工具，但是我想要的细节水平那些工具不能做到，所以最后，我选择用Maya的四边形绘制工具手动创建一个新的拓扑。手动完成它确实需要相当多的时间，在那种情况下需要5-6个小时，但我觉得最终渲染的细节水平是值得的，我也想公正地对待原始作品。
Materials in Substance 3D Painter
Now, with the low-resolution model done, I was able to bake a good Normal map in Substance 3D Painter with the high-resolution scan data, I also baked the color data from the scan. For the final material, blending the color data with a copper material for the statue and a granite material for the base, I was able to fine-tune the mix between the two.
现在，随着低分辨率模型的完成，我能够在Substance 3D Painter中使用高分辨率扫描数据烘焙一个良好的法线贴图，我还烘焙了扫描的颜色数据。最后，我将颜色数据赋予铜材质的雕像和花岗岩材质的底座，并进行微调。
Final Renders
最终呈现
For the final render, I had to choose a tool. I wanted to render it in real-time because I mainly do work related to video games. I do love my Unreal Engine, but it can become time-consuming to get renders out of it, so I decided to go with Marmoset Toolbag, which can get you some professional-looking renders in a few minutes. So here’s the final render of this photogrammetry project.
对于最终的渲染，我必须选择一个工具。我想要实时渲染它，因为我主要做与电子游戏相关的工作。我确实很喜欢我的虚幻引擎，但它会变得非常耗时，所以我决定使用Marmoset Toolbag，它可以在几分钟内让你得到一些看起来很专业的渲染。这是这个摄影测量项目的最终渲染图。
Conclusion
结论
In conclusion, I can say that some things I did could be improved in a future photogrammetry project. Choosing the right day with the right lighting conditions can make a great difference. Also, one thing that I've learned is that close-up shots do really work well and stitching the model in ZBrush also works with the DynaMesh tool, so I would probably make more close-up shots.
总之，我觉得不足之处可以在未来的摄影测量项目中得到改进。选择合适的日子和合适的光照条件会有很大的不同。此外，特写镜头确实很好用，它可以在ZBrush中缝合模型，也可以与DynaMesh工具一起工作，所以我可能会拍摄更多的特写镜头。
I am happy with the final result, I think at the end of the day, we accomplished our goal of scanning the statue of Athena and rendering it in a real-time render engine. Huge thanks to Jonathan Bélisle for his help with the photoshoot, I could not have done it without his photography skills.
我对最终的结果很满意，今天，我们完成了扫描雅典娜雕像并在实时渲染引擎中渲染它的目标。非常感谢Jonathan Bélisle对照片拍摄的帮助，如果没有他的摄影技术，我不可能做到这一点。
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