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This page last changed on Jul 16, 2008 by brian.
Dives
About the Data
Image Orientation
From an email from Kiran Murthy on 2008-07-16:
Brian Schlining: What is the heading relative to? It looks like its the initial direction of the ROV but I just want to confirm that. Which direction is positive, clockwise or counter-clockwise?
Kiran: Indeed, the heading is relative to the initial direction of the ROV. Thus, we have:
rovHeading = initialHeading + relativeHeading
We're taking images from the main camera pointed straight down. Thus, the top of the image corresponds with the ROV's forward direction, and positive heading corresponds to the ROV rotating from north to east,
Brian Schlining: Also, if the camera has 0 pitch and 0 roll where is it pointing? What directions are positive pitch and roll?
Kiran: Zero pitch/roll corresponds to the camera pointing straight down. Positive pitch is ROV bow up and positive roll is ROV port up.
To clarify a bit further, you can imagine a "camera frame" with its origin at the image center. In this frame, x points toward the top of the image, y points toward the right side of the image, and z points into the image (away from the camera). Heading/pitch/roll then form a ZYX Euler angle triplet that describes the orientation of the camera frame with respect to a frame oriented (x,y,z) = (North,East,Down).
-Kiran
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