You Can Get There From Here – Creating 3D models with Photorealistic textures from the e57 file format

Fred Leighton, University of Wisconsin-Whitewater, USA

Abstract

Keywords: E57, LiDAR, RealityCapture, 3D Models, Remote Sites, Education

Abstract

 This is an introduction to developing 3D models with photorealistic textures for use in digital projects, for example, animation, cinematics, augmented reality and virtual reality. A development process is demonstrated, starting with an e57 file, a format that includes laser scan data and images, including metadata, and results in an optimized, textured mapped 3D model asset.

Keywords

e57, LiDAR, RealityCapture, Blender, Unity, 3D models with photorealistic textures, cultural heritage, laser scans, point cloud, photogrammetry, development pipeline, Chumash rock art

Introduction

Definitions / Terminology

e57 data

e57 data files include point clouds, images, and metadata generated by 3D imaging systems, including laser scanners and imaging systems. The file format is specified by the ASTM, an international standards organization, and it is documented in the ASTM E2807 standard. The current version is 1.1.312 (http://www.libe57.org/)

Point Cloud data

A point cloud is a set of data points in space. The points represent a 3D shape or object. Each point has its set of X, Y and Z coordinates.

(https://en.wikipedia.org/wiki/Point_cloud)

LiDAR

Light Detection and Ranging (LiDAR) is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to the Earth. These light pulses—combined with other data recorded by the airborne system — generate precise, three-dimensional information about the shape of the Earth and its surface characteristics.

A lidar instrument principally consists of a laser, a scanner, and a specialized GPS receiver. Airplanes and helicopters are the most commonly used platforms for acquiring lidar data over broad areas. Two types of lidar are topographic and bathymetric. Topographic lidar typically uses a near-infrared laser to map the land, while bathymetric lidar uses water-penetrating green light to also measure seafloor and riverbed elevations. (https://oceanservice.noaa.gov/facts/lidar.html#:~:text=Lidar%2C%20which%20stands%20for%20Light,variable%20distances)%20to%20the%20Earth.)

Photogrammetry

Photogrammetry is the science and technology of obtaining reliable information about physical objects and the environment through the process of recording, measuring, and interpreting photographic images and patterns of electromagnetic radiant imagery and other phenomena. Digital image capturing and photogrammetric processing includes several well defined stages, which allow the generation of 2D or 3D digital models of the object as an end product. (https://en.wikipedia.org/wiki/Photogrammetry#:~:text=Photogrammetry%20is%20the%20science%20and,radiant%20imagery%20and%20other%20phenomena.)

About the sample data set for demonstration

Chumash Painted Cave State Historic Park, Native American rock art

The walls of this small cave carved from towering sandstone boulders contain some of the finest remaining rock art created by Chumash Native Americans.  A steep path leads to the cave entrance, which is protected by heavy iron grillwork. Anthropologists estimate that the paintings date to the 1600’s and earlier.  The meaning of these enigmatic images has been lost. (https://www.parks.ca.gov/?page_id=602)

Intended Audience

 Designers and developers of digital content who want to work with accurate point cloud data and images for creating 3D models with photorealistic textures. Experience with software tools for design and development of 3D models and textures, and authoring tools that include 3D models and textures is recommended.

Session Goals

To demonstrate a development process for creating lower resolution 3D models with photorealistic textures from an e57 data file source.

Development

Step by Step Example

In this example, a low polygon texture mapped 3D model is developed starting with e57source data from the Chumash Painted Cave at Painted Cave State Historic Park, a California State Park located near Santa Barbara, California.

Step One

Locate an e57 source file.

e57 files can be obtained from websites at no cost. For this example, the source file is from the Open Heritage website.

Step Two

Import the file into RealityCapture 1.1 for viewing, editing, and exporting.

Import the e57 file to RealityCapture. The software interface can be configured to access a number of different views and data sets including 2D images, point cloud data from LiDAR laser scans, and metadata. Tools, settings, and workflow selections are in the ribbon on the top of the interface. Workflow choices are presented in a basic set of commands, and, in more detailed tool settings. Here are views of the 2D images combined point cloud data to create an initial rendering of the data.

Step Three

Align data to create 3D model

After applying tools to align the images and scan data, a flat shaded texture is created.

Step Four

Apply images to create view of model with photorealistic textures.

Step Five

Edit the model

Use selection tools to delete polygons, resulting in edited model for export.

Step Six

Prepare model for UV texture mapping.

Step Seven

Export model with texture from images.

Exporting with the FBX model format will include the UV coordinates and mapped texture image in PNG format, which can then be easily imported to other applications, keeping the texture map placement intact with the model.

Step Eight

Import the FBX model to 3D modelling tools, for example, Blender, an open source software tool, and Unity, an interactive 3D authoring tool for games, augmented reality, virtual reality and cinematics.

Resources

Software

RealityCapture 1.1 (PC only)

https://www.capturingreality.com/

Blender

https://www.blender.org/

Unity

https://unity.com/

e57 file sources

Open Heritage

https://www.openheritage3d.org/

 Lib E57

http://www.libe57.org/data.html

Chumash Painted Cave State Historic Park

https://www.parks.ca.gov/?page_id=602