Blockbuster Scanning: Using LiDAR for Joker & John Wick

Author: John Ashby

John Ashby is LiDAR supervisor at光环外汇, a company providing on-set data acquisition services for the film and gaming industries. Ashby has worked on Hollywood blockbusters including小丑和John Wick: Chapter 3 – Parabellum，捕获胶卷和位置的3D扫描。在胶卷制作过程中，捕获的扫描数据以多种方式使用，尤其是用于创建VFX（视觉效果）。

随着时间压力，这项工作的主要挑战之一，阿什比使用Leica ScanStation P50长距离3D激光扫描仪，用于高分辨率，快速扫描。有了很多数据，他使用了狮子旋风software for easy processing of large numbers of scans.

The benefits of reality capture in the film industry

使用激光雷达和其他激光扫描技术正在帮助电影业提高生产和后期制作的效率，同时，创造了更现实的视觉效果。扫描胶片或位置提供了准确的记录。可以用来帮助匹配摄像机角度。这样可以确保连续性并为建立任何虚拟资产（例如数字设置扩展）设定基础。

Using LiDAR to improve the realism of VFX

Having a scan as a reference point helps VFX teams create more seamless effects. Previously, footage of a film set would be used to make a virtual recreation in 3D. To add realistic-looking effects, the technicians would need to match the same camera angle and motion as in the original shot (‘match moving’). Without laser scanning crews would take detailed measurements but couldn’t achieve 100% accuracy. By capturing the entire 3D world of any shot, LiDAR and laser scanning combined offer a precise map from which to work.

阿什比（Ashby）从他的工作中举一个例子小丑.“I scanned a lot of sets, including Arthur’s apartment, and the TV set for the Murray Franklin talk show, which I scanned because there was all this CG blood that had to get added in post and this allowed them to get a perfect camera track of those sets.”

足总st scanning speeds are required for scanning in a frantic environment

Speed is critical for scanning on set; with large crews and huge running costs, film production can’t be delayed by data collection. : “It’s all about what’s the most data you can get in the fastest amount of time without holding up the production,” Ashby explains.

在进行工作时John Wick 3: The Continental,阿什比只有四个小时来扫描和拍摄主要位置。“大陆大陆的建筑物是布鲁克林的一个汉森广场，这是巨大的。这只是与时间的纯粹竞赛。”阿什比需要获取尽可能多的数据，并准备停止并开始扫描以适应拍摄，有时甚至在镜头之间抓取扫描。

Ashby explains his process of LiDAR scanning on set or location, “I tend to start with a quick blitz of the particular environment to get a ‘registration’ of it. This is just lots of fast low-resolution scans; it’s just so I know in the worst-case scenario, I’ve got a full registration of the environment. Then I’ll go around and do my luxury scans from different ‘stations’...upping the resolution and sampling quality in order to get the more distant and reflective surfaces.” This is where Ashby uses the ScanStation P50, which he finds twice as fast as the other laser scanners he uses for shorter range work.

Ashby解释说：“我拥有Leica Geosystems扫描仪设置的方式是，在10米处的分辨率为每0.6厘米1分……您正在捕获更多的数据，” Ashby解释说。“扫描仪P50的数据令人难以置信地干净 - 非常快。”

Using LiDAR scanning to improve continuity

By creating a virtual 3D version of the filming environment, LiDAR scanning makes it easier to see the position of an object from different angles, and to make sure that things are where they are supposed to be. “What LiDAR really helps you do is, when you’re working on multiple shots from different camera angles, you can track everything to the LiDAR data and it snaps all the cameras into the same world space,” Ashby explains. “It means that if you put something in 3D space in one shot, it will be in the same 3D space in all the other shots.”

Using an example of a scene from小丑,Ashby talks about a scene with a lot of cuts. The scan helped the technicians to match CG blood from different angles, “What it means is that the blood in shot A lines up perfectly with the blood in shot B.”

易于使用的软件对于检查大量扫描至关重要

The need to stop and start scanning can complicate the process of registering scans together. “All your scans can get really jumbled around. So a good logging system is key and then it’s much easier when you have to manually align your scans after,” clarifies Ashby.

Ashby使用Cyclone软件进行后处理，并喜欢它允许手动对齐的控制量。“旋风软件包非常快。您只需将它们覆盖[扫描]，您很快就将它们排成一行，这几乎是……您可以在大约几个小时内完成大约80张扫描。”

在建筑或制造等其他行业中，扫描将用于创建高度详细的环境3D模型，但是，在电影行业中，OBJ（多边形网格）通常是首选的输出，其中包含所有必需的细节；“作为一种格式，OBJ非常不可破，通常是最要求的可交付方式。”

然后，阿什比（Ashby）的工作就完成了，因为他将扫描提供给其他从事制作的其他工作：“我通常将所有内容都交给生产或视觉效果工作室。”LiDAR主管将激光扫描仪打包到飞行案例中后，准备下一盘中使用Leica Geosystems激光扫描仪。

Based on:Lidar scanning for Joker and John Wick