你是不是觉得如今电影和电视里的3D技术已经非常了不起了？别着急，先去去看看全息沙盘再说吧。这项技术全名叫城市光学沙盘显示系统（Urban Photonic Sandtable Display），由美国国防部（the Defense Department）下属的研究机构国防高级研究规划局（DARPA）资助，主要用于作战计划制定，能够产生360度的3D图形（无需佩戴3D眼镜）。虽然负责研发该技术的Zebra Imaging公司表示，至少还需3年时间，沙盘技术才能用于外科手术规划、游戏等商业应用，但这并不妨碍我们现在就开始畅想各种可能性。以下是这技术的工作原理：

    虚拟模型：使用标准设计软件或光线侦测和测距设备（Light Detection and Ranging，简称LIDAR）创建高精度3D渲染模型，LIDAR能够使用不可见的激光全面扫描现实世界里的建筑和物体。

    准备全息图：利用安装在普通计算机上的专有软件插件，将3D图形转换成支持全息图的文件。在这个阶段，用户可以放缩、旋转全息图或是改变光照参数。

    显示：显示器内部的处理器和图形处理单元能处理这些数据，随后通过光调制器和一系列镜头产生由数百万个全息元素hogel（即3D图形像素）组成的图像。

    If you think today's 3-D technology in movies and TV shows is cool, wait until you see your first hologram table. Funded by DARPA, the Defense Department's research arm, for battle planning, the Urban Photonic Sandtable Display produces a 360°, 3-D image (no glasses needed). Zebra Imaging, the company that is developing the technology, says it'll take at least another three years before this table is set for business applications like surgical planning or even gaming, but that won't stop us from thinking about the possibilities now. Here's how it works.

    Virtual models: Detailed 3-D renderings are created from standard design software or Light Detection and Ranging (LIDAR) devices that sweep real-world buildings and objects with invisible lasers.

    Prepping the hologram: A proprietary software plug-in loaded onto a standard computer converts the 3-D image into a hologram-friendly format. During this stage, users can zoom in or out, rotate, or change the lighting.

    The display: Processors and graphics-processing units inside the display crunch the data and send it through a light modulator and a set of lenses to create an image made up of millions of "hogels," the 3-D equivalent of pixels.