Rotation of 3D Objects: The Importance of Center of Rotation

Joshua Coyan¹ and Stephen Reynolds²
¹Chevron Corporation, Houston TX
²School of Earth and Space Exploration, Arizona State University, Tempe AZ

Abstract

A primary data set of geoscientists in the petroleum industry is the 3D seismic cube, a geophysical representation of the subsurface, and 3D cognitive skills are critical to the success of geoscientists in interpreting these seismic data. However, in addition to 3D spatial ability, proper understanding and adept manipulation of a 3D seismic cube is another important aspect of visualizing geometries and relationships between stratigraphy and structures in the subsurface Our previous research highlights the importance of the center of the scene as a focal point and our planned research explores how this concept applies to subsurface interpretation from 3D volumes.

In our previous research we eye tracked introductory geology college students while they watched a narrated slide show featuring static landscape photographs containing a key geologic feature, such as a fault or joint set. Our results indicated that individuals primarily visually attend to the center of a scene with little to no fixations occurring on the periphery of the scene. These results have implications for teaching and learning from photographs and images, but have limited applicability to 3D visualization. Consequently, in our current study we aim to better understand how students visually interact with 2.5D rotating landscapes.

In this current study, we evaluated four-case studies involving students watching a narrated video of rotating landscapes. The participants were four introductory geology students at a large southwest university. They were eye tracked while watching a narrated video featuring 5 landscape-block models. The block models were intermittently rotated 360 degrees around a vertical axis. Rotation occurred in a way that the block model would rotate in 10-degree increments for 90 degrees and then pause for several seconds and then rotate in 10-degree increments again. This style of rotation would occur repeatedly until the block model had completed 360 degrees of rotation. In all cases, the vertical axis was located in the center of the block model.

Preliminary analysis of our data set indicates that before the rotation began, the participants generally fixated across the landscapes to areas referenced by the narration (e.g. along river terrace systems). Fixations during rotation were constrained to a smaller visual angle closer to the center of rotation and appeared to return to the apparent location of the vertical axis after 1 to 4 fixations. This constant cycling of fixations back toward the center of rotation may indicate a need to "anchor" understanding of the rotating objects.

As a next step in this study, we plan to compare visual behaviors between novices (the introductory geology students already eye tracked) with those of petroleum industry experts. Accordingly, our next step will be to eye track industry earth scientists while visually inspecting a seismic section oriented in a crossline and inline view (cross sections perpendicularly oriented within a seismic cube). After allowing the earth scientist to inspect the static view, the seismic section will be rotated about a horizontal axis and then rotated about a vertical axis. In some cases the axes will be located near the center of the rotating cube (also the point of intersection of the inline and crossline sections, which is a predictable location for the axes to be located). In other cases, the axes will be located off center of the cube (an unpredictable location for the axes to be located), creating a wobbling effect when rotated. Our goal is to answer the questions, what is the affect of the location of the center of rotation on the visual attention of industry geoscientists and how distracting is it to their work when not positioned in a predictable location?

It is our interpretation that if the center of rotation of a 3D object is not located in a predictable position (the center of the scene), working memory will be required to rectify and map what may appear as a random axis location. Once centering of the axes is restored to the center of the view, a mental anchoring may occur allowing visual attention and working memory to focus back to the task at hand, seismic interpretation.

AAPG Search and Discovery Article #120140© 2014 AAPG Hedberg Conference 3D Structural Geologic Interpretation: Earth, Mind and Machine, June 23-27, 2013, Reno, Nevada