The Accuracy of Mobile Mapping Systems

I have had a number of discussions over the past few weeks about the absolute accuracy of mobile mapping systems. This is a very important issue as it goes to the integrity of the entire industry and one that it would seem experts should be able to come to a consensus on.

I think we can all agree that the absolute accuracy cannot be better than that of the scanner, or can we? It seems that some vendors are claiming to do better than this. When the error associated with the trajectory is factored in this would be difficult to understand.

Please provide your thoughts.

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3 Responses to The Accuracy of Mobile Mapping Systems

  1. I think you are right for the bottom line. I would add that the absolute accuracy should be coupled to the navigation system itself and to the effort to register the could to control points. Scanner x Navigation x Registration = Accuracy.

  2. Jim Brainard says:

    I thought it would be worth at least starting out with a basic understanding of a commonly accepted method of calculating a project accuracy.
    First thing to do is look at our own accuracy: i.e., system mounting and cartesian offset calculations; calibration; environmental parameters effecting equipment.
    Second thing to do is look at each component of the system and identify its individual absolute accuracy ability. We are really identifying uncertainty in a measurement for each component: laser scanners; GPS; IMU; DMI.
    Third step is to calculate a System Accuracy. Like the Pythagorean Theorem, the System Accuracy is equal to the square root of the sum of the squares of each component’s Absolute Accuracy.
    Now there really is one more data set evaluation that should be taken into account when looking at results. This step entails taking the LiDAR point cloud and refining it to a set of more precicely established identifiable coordinates positions and performing a best fit translation of the LiDAR data. This enables us to take a closer look at how well we can state our results to a referenced constraint and express our results as a 2 sigma (95% confidence) of the collected LiDAR data set.
    Now as I see it, we need to know both the System Accuracy and the resulting data set refined statement of accuracy so that the end user can understand how using the data will effect them.
    Just one mans opinion.

  3. charles smith says:

    or you could compare derived absolute values to known values…….perish the thought!

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