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Lesson 1: Visualize 3DEP Lidar Data with uniDEM

This tutorial illustrates methods to load, view and interact with 3D point clouds and will cover the following topics.

The sample data used in this lesson is 3DEP lidar data in two LAZ files in LAS version 1.2 and located in Madison, MS, USA. Prior to commencing this lesson, please perform the following:

This lesson will take approximately 20 minutes.

The following video executes the steps in the tutorial.

1. Install and Open uniDEM

  1. Install uniDEM using one of two options:
    • uniDEM Microsoft Download Recommended method: Signed app and automatic updates
    • Novlum uniDEM Download
      Alternative: Unsigned and manual updates
  2. Open uniDEM
unidem layout

Help references:

Window Overview

2. Load Lidar Point Clouds

  1. Click uniDEM icon
  2. Click Load LIDAR
  3. Open the unzipped working data folder
  4. Select both LAZ files
  5. Click Open
Load laz point cloud
  1. Click OK to maintain LAS v1.2
  2. Click Yes to all files into single dataset
  3. Enter Madison for the combined dataset name
  4. Data is displayed in the Table Of Contents (TOC)
name lidar dataset

Help references:

Load LIDAR | Data Management | Table of Contents

3. Display Lidar Point Cloud

Display Both LAZ Files

  1. Right Click Madison in the TOC
  2. Click Check All
show lidar dataset

Initial Lidar Point Display

  1. Lidar points for both files are displayed top down (2D)
  2. Points are colored based on the LAS classification in the point metadata
Notes:
  • Points density and display size are set conservatively by default (see next step)
  • If no Class exists points are colored by elevation
displayed las classifications

Set Point Size and Density

  1. Click the LIDAR tab
  2. Click the Point Size dropdown and set to large.
  3. Click the Density dropdown to render more or less points
    Note: Increasing density reduces render rates
uniDEM strides lidar points for rendering performance.
displayed las classifications

Help references:

Table of Contents | Point Density | Point Size

4. Interact with 3D view

  1. Click into data view
  2. Rotate: Right click and move mouse left or right
  3. Tilt Right click and move mouse up or down
  4. Move: Left click and move mouse in any direction
  5. Zoom: Scroll wheel mouse forward/backward
  6. Toggle 2D/3D: Press key 2 and 3
3d interaction uniDEM

Help references:

Data Views | 2D/3D Display

5. View Lidar Point Detail

Place the cursor is placed over a lidar point to see point details above the cursor and in the TOC.
  1. Lidar class is displayed over cursor
  2. Elevation (Z)is displayed over cursor
  3. Source Lidar file is displayed in TOC
  4. Lidar Class is displayed in TOC
  5. LAS metadata including:
    • Edge of Flight
    • Intensity
    • Keypoint
    • Point Source ID
    • Return
    • Scan Angle Rank
    • Scan Direction
    • Synthetic
    • Time
    • User Data
    • Withheld
    • Overlap (LAS v1.4)
lidar point detail

Help references:

Table of Contents | Data Views

6. LAS Class Profile

Profile Entire Dataset

  1. Click LIDAR tab
  2. Click Class Profile button
  3. Click OK to use the Madison dataset
  4. Click Select All to select both LAZ files
  5. Click OK
The dialog presents the following information:
  • Total number of points
  • Each LAS Class type in the selected datasets
  • The count for each LAS class
Note: This project contains misclassifications, for example buildings are classified as Medium Vegetation (4) and Overlap as Reserved For ASPRS (11).
las class profile

Profile Selected Area

  1. Press r on keyboard to enable rectangle drawing tool
  2. Hold Shift + Left click while moving mouse to draw a rectangle
  3. Click Class Profile button
  4. Click OK to use the Madison dataset
  5. Click Select All to select both LAZ files
  6. Click OK
The dialog presents the following information for only points within the rectangle:
  • Total number of points
  • Each LAS Class type in the selected datasets
  • The count for each LAS class
Note: This project contains misclassifications, for example buildings are classified as Medium Vegetation (4) and Overlap as Reserved For ASPRS (11).
las class profile with selection

Help references:

Class Profile | Rectangle Drawing Tool

7. Turn On/Off Lidar Points by Class

  1. Click LIDAR tab
  2. Click Show/Hide Classes button
  3. Click Ground (2) in the selection dialog
  4. Hold Ctrl and click Water (9) in the selection dialog
  5. Click OK

The view turns off all lidar points that are not of class Ground(2) or Water (9).

Notes:

  1. The remaining points are remain loaded, but not visible
  2. Independent data views can present different classes
las class profile

Help references:

Show/Hide Classes

8. Change Lidar Point Colors

Color By Elevation

  1. Within the LIDAR tab
  2. Click Color button
  3. Select Color By Elevation
  4. Click OK to use the Madison dataset
  5. Click Select All to use both LAZ files
  6. Click OK
  7. Click OK to select the Jet color scheme
  8. Click OK to select Auto color scale
  9. Click OK to use 1 as the lowest percentile
  10. Click OK to use 99 as the lowest percentile
color las points by elevation

Color By Intensity

  1. Within the LIDAR tab
  2. Click Color button
  3. Select Color By Intensity
  4. Click OK to use the Madison dataset
  5. Click Select All to use both LAZ files
  6. Click OK
  7. Select Gray from the drop down in the color scheme dialog
  8. Click OK to select Auto color scale
  9. Click OK to use 1 as the lowest percentile
  10. Click OK to use 99 as the lowest percentile
color las points by intensity

Help references:

Lidar Point Color