Point thinning and scalability of a LAS dataset

Use point thinning and scalability option for a LAS dataset to optimize performance in ArcGIS Pro. The LAS dataset is scalable, allowing you to work with large point cloud datasets quickly and efficiently. Rendering very large point sets or TIN-based surfaces is generally difficult, partially due to hardware limitations. A benefit of LAS datasets is that you render the areas you need to visualize at an optimized point resolution.

On-the-fly surface construction, display, and analysis are faster for smaller-scale applications because only a thinned subset of the data is required. LAS dataset tools facilitate the use of large point collections, such as lidar, that normally pose display problems. Scalability is achieved through random point thinning. The original data is not moved or averaged in any way. You can take advantage of a LAS dataset pyramid structure to improve display performance of a LAS dataset.

Consider rearranging the LAS points using the Extract LAS geoprocessing tool and rewrite the LAS files. Doing so will order the point records into spatial clusters that are optimized for reading the files and will dramatically enhance their display performance throughout the ArcGIS platform. The Rearrange parameter is also available on the Convert LAS and Tile LAS tools.

Typically, the LAS points are displayed as a thinned representation of the full-resolution point set. You can quickly zoom to the full resolution using the Zoom To Full Resolution command on the context menu of the LAS dataset layer. Right-click the LAS dataset layer in the Contents pane and click Zoom To Full Resolution. The Zoom To Full Resolution option is only available in a 2D view.

The LAS Dataset Layer tab set controls the LAS dataset layer's drawing behavior and point thinning. The Point Thinning group controls the resolution of the LAS dataset. The Point Thinning group is available in a 2D or 3D view.

Access point thinning options

Follow these steps to access the Point Thinning group:

  1. Select a LAS dataset layer in the Contents pane.
  2. On the LAS Dataset Layer tab set, in the Point Thinning group, click the applicable point thinning options for the selected LAS dataset layer.

Full Resolution—When Use scale to control full resolution is checked, a scale threshold can be set in the Full Resolution Scale window. This is used to control when the LAS dataset renders itself without thinning, using 100 percent of the LAS points. It is used when the map scale is equal to or greater than the scale you specify. The point limit is still honored; therefore, if the number of estimated points for the current extent exceeds the limit, the LAS dataset thins itself and will not draw using all the data. When this occurs, an asterisk appears next to the data percentage listed for the layer in the table of contents. When the map display scale is less than the full-resolution scale, thinning occurs based on the setting on the Point Density slider.

Display Limit—Applying a point limit sets a size limit to the number of points used in the triangulation of the LAS dataset layer surface. The default value is 4,000,000. If, for a given display extent, use of the settings results in a surface that exceeds the specified point count, the layer switches to be more generalized.

Density—The density of points enforced by the LAS dataset. This is set interactively by using the slider. Move the slider to the left for a coarse surface and to the right for a more fine or full-surface resolution. As you move the slider, the density of the points on-screen changes from Min to Max.

Dynamic level of detail

The dynamic level of detail option for a LAS dataset will maximize the number of LAS points that are drawn when it is filtered by class code or returns. The default LAS point display assumes there’s no filtering applied. Therefore, if there is a filter applied, it will draw fewer points than it actually can while remaining in the specified point budget. For example, you filter your LAS dataset by ground points only and 50 percent of all points are ground. The default behavior ignores that, thinking all points are being drawn. The result is that it draws fewer ground points than it actually can. If you want to maximize the number of points that are drawn while displaying points using a filter, turn on dynamic level of detail. It takes longer to render points with dynamic level of detail turned on, therefore you will want to use it only at specific moments to increase detail where and when needed. The dynamic level of detail option only applies to LAS datasets displayed in a Scene view. The LAS dataset being rendered must have a valid pyramid.

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