Classifying by Groups in TerraScan

Beginning in 2014, some grouping tools were introduced to TerraScan.  Those tools applied to mobile LIDAR applications as they were aimed at classifying moving cars and trees. In late 2016, additional grouping tools were introduced to enable a new method of conducting above ground classifications in airborne LIDAR datasets beyond the standard classification routines.  Prior…

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Setting the USGS Overage Flags in TerraScan

Introduction For many years users have been working with the concept of ‘cutting overlap’ in LIDAR data production. With the onset of LAS v1.4 and the USGS LIDAR Base Specification, the way in which this concept is implemented has significantly changed.  Specifically, USGS standards require a change in the way overlap points are managed and…

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Control Point Statistics in TerraScan

Terrasolid software offers a variety of ways to gauge the accuracy of LIDAR and imagery data.  From using control points to determine the vertical accuracy of a ground surface, tie lines to measure and correct the mismatch between overlapping flight lines, and tie points to correct aerial imagery positions, each of these tools provide the…

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Waveform Data in TerraScan

Many users of LIDAR use discrete return systems for their production, however, many systems are capable of capturing the full waveform of the energy returned from an outgoing laser pulse. The figure illustrates a laser pulse directed through a tree.  Different portions of the laser energy are backscattered/returned by various surfaces: branches, twigs, leaves, and…

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Rut Analysis using Terrasolid

One of the many applications that are suited to the use of mobile LIDAR analysis, is the identification and measurement of ruts and potholes. Here we will discuss the preparation of the data, ways to visualize rutting, the classification of pot holes, and the production of road section parameters. As with any kind of LIDAR…

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Vertical Accuracy Reporting in TerraScan

In November 2014, the American Society for Photogrammetry and Remote Sensing (ASPRS) released an updated standard, Positional Accuracy Standards for Digital Geospatial Data, to tie together past experience with current industry practice of preparing data, but not plotting the resulting maps. The new standard provides guidelines for calculating both the vertical and the horizontal accuracy.…

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Geiger-Mode LIDAR Workflow Review

Geiger-mode lidar data is getting a lot of press lately as the “next big thing” in airborne data collection.  Unlike traditional lidar sensors, which we will call “linear-mode lidar” for convenience, Geiger-mode sensors use a different detection method in the receiver – the “Geiger-Mode” part – to enable much higher data collection altitudes and higher…

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GPS time in TerraScan

In TerraScan the Time conversion can convert to/from GPS seconds-of-week, GPS standard time  and GPS time. Projects can store GPS seconds-of-week, GPS standard time  and GPS time in LAS 1.2, and later formats, or Fast Binary. ‘GPS seconds-of-week‘ time stamps are between 0 and 604800, where the clock resets at midnight Saturday night to Sunday morning.…

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Recommended Block Size and RAM

When designing block boundaries in TerraScan it is necessary to break the dataset up into manageable block sizes. Depending on the task you wish to perform on the dataset you may desire different block sizes, but from an overall perspective one can recommend the following as general guidelines. 32-Bit (v8, v8i) 64-Bit (CE) Recommendation 20…

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Classify Below/Above Curve

Before running Detect Wires it can be helpful to clean up the potential wire points to help prevent false positives from being detected. The Classify Above/Below line tool can be useful for this, however, the View Tower Spans contains an additional classification tool Classify Above/Below Curve which can be more efficient. The Classify Above/Below Curve tools…

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