Frequently Asked Questions

Mobile LiDAR Specifications:

Q. What are the measurement frequencies of Michael Baker International’s Mobile LiDAR systems?
A. Each system utilizes 2 lasers that can each measure up to 600,000 points per second.  The total maximum measurement frequency on each system is 1,200,000 points per second.  The frequency is configurable based upon the collection requirements and can be set to capture at 75, 150, 300 or 600 kHz.

Q. How many measurements can each system receive for every laser pulse?
A. Each system can measure up to 4 returns (1st, 2nd, 3rd, and last) for each laser pulse. Theoretically, this yields the ability to measure up to 4.8 million returns per second.

Q. What is the range of the lasers?
A. Each laser can accurately measure a target up to 200m (656’) from the sensor-head, in all directions.

Q. What is the laser precision?
A. The stated, repeatable precision of each laser is ≤5mm.

Q. How wide is the Field of View?
A. The system has a complete 360° Field of View.

Q. What are the onboard camera specifications and capture rates?
A. Michael Baker International’s Lynx systems includes four 5 mega-pixel cameras capturing up to 2 frames per second each, that can be positioned at various locations and angles on the vehicle.  In addition, each system includes a PointGrey Ladybug 5 spherical camera – six 5 mega-pixel camera array.   The Ladybug camera provides panoramic, spherical and rectified formats of imagery.

Q. How often does the IMU (Inertial Measurement Unit) measure?
A. Our systems have IMU’s that measure the attitude (pitch, yaw, and roll) and acceleration 200 times per second (200Hz).  One system includes an ITAR-free FMU P301 that provides more flexibility to service clients outside the United States.

Q. Can you see the laser, and is it safe to look at?
A. The laser sensors produce an IEC/CDRH Class 1 light beam. The light beam is invisible to the naked eye, and the Class 1 designation means that it is “eye-safe”. Therefore, the lasers can be operating while drivers and pedestrians are present without presenting any safety hazard or distraction.

Mobile LiDAR Applications:

Q. Can Baker’s Mobile LiDAR systems be mounted on other platforms?
A. The entire survey platform, is removable and fully capable of being mounted on an off-road vehicle, boat, hi-rail, or speeder car. With this flexibility, Michael Baker is able to perform railroad assessments, beach erosion surveys, mine surveys, other coastal environment surveys, and many more where surveying with a conventional automobile is not feasible.

A. Yes, data from all three LiDAR categories (aerial, mobile, static) can be integrated to completely saturate a project area from the sky to the ground and within buildings. Traditional survey data can be integrated as well; after all, each methodology is simply generating survey information.

How it Works:

Q. What is the vehicle’s primary method of positioning?
A. The system utilizes an onboard dual-antenna high-accuracy GNSS receiver to provide accurate vehicle positioning.

Q. What are the other means for positioning?
A. Our Mobile LiDAR systems are also equipped with an inertial measurement unit (IMU) and distance measurement instrument (DMI). The IMU measures the attitude (roll, pitch and yaw) of the vehicle by measuring changes in direction around the X, Y and Z axis 200 times per second.  The DMI is used to calculate the distance traveled by the vehicle by measuring the revolutions of the wheel 1,024 times per second. The DMI is also used to supplement GPS and IMU drift by communicating to the system that the vehicle is stationary.

Q. What is the primary function of the on-board cameras?
A. The onboard cameras are utilized to perform three primary functions: 1) by pairing the cameras with the lasers, we are able to georeference the images to the LiDAR data, and colorize the resulting point cloud with the RGB values from the image pixels; 2) the camera images also serve as a validation tool, by enabling our processing staff to rapidly identify features and objects within the point cloud with the referenced photos; and 3) certain software tools utilize the calibrated imagery for additional feature extraction and attribution capabilities.

Q. Can data be accurately collected in a tunnel without GPS?
A. Even with the loss of GPS signals within a tunnel, our Mobile LiDAR systems will produce accurate results.  During a GPS outage, the DMI and IMU automatically take over primary positioning duties.  Working in unison, the DMI provides the distance traveled, while the IMU supplies the measured rate of turn; enabling the system to accurately calculate the vehicle’s trajectory.  The need for ground control still exists and our team can help identify control requirements.

Collection Specifications:

Q. Can the Mobile LiDAR system operate at night?
A. Yes, because the system utilizes an active laser, we can operate at night. Night surveys are very favorable, especially for road corridor projects, due to lower traffic volumes and decreased number of obstructions (such as cars) that could block the laser from striking the desired target. Keep in mind that the cameras are not used at night, so simultaneous collection of images with the point cloud is not possible. If photography is desired, collection would also occur during daylight hours, or where permissible, at night with onboard high-intensity lighting.

Q. Can the Mobile LiDAR system operate in rain or snow?
A. Yes. However, Baker makes all attempts not to operate the system in poor weather conditions in an effort to preserve the operational integrity of the equipment and ensure the data collected is of the highest quality. Because the system is able to collect a large amount of data in a short period of time, our team is usually able to work around adverse weather conditions through careful project planning and execution.  With the ownership of two systems, we can deploy both systems on larger projects to take full advantage of more favorable conditions.

Q. Can the lasers penetrate or produce returns off of a water surface?
A. The system will not capture returns through water that has ponded on a surface.  Additionally, no usable data is captured on the surface of ponded water.  The area appears as a void in the LiDAR point cloud.   

Q. Can the lasers penetrate a building to collect data within the building?
A. No. The laser will not penetrate any hard surfaced building material beyond its external face. 

Q. How are the lasers positioned to capture all features in a single pass?
A. The lasers are oriented to produce an “X” pattern. This configuration enables a full 360° Field of View, as Sensor 1 will capture the front face of an object during the approach, and Sensor 2 will capture the back face during the departure.  See figure below.

Mobile LiDAR Sensor Configuration

Q. How much area can be surveyed in one day?
A. Depending upon project requirements and local conditions, our system can capture tens to hundreds of miles per day.

Post-Processing Specifications:

Q. What software can you use to view LiDAR data?
A. There are a number of commercially available software packages that can be used to view and manipulate LiDAR data, including many GIS applications, as well as several free-ware applications that enable viewing-only capabilities.  Our team can providefurther assistance upon request.

Q. What is the time frame for post-processing raw LiDAR data?
A. There are a myriad of variables that can directly affect the amount of processing required for a particular project (size of area, amount of ground control, number and type of deliverables, etc.), but a general rule of thumb to consider is a 2:1 ratio; whereas it will take approximately twice as long to generate a LAS file (standard format for LiDAR data), as it did to capture the data in the field. For more detailed and strictly controlled deliverables including colorized point clouds, animations, planimetrics, contours, etc., the post-processing time will be much greater.

Product Deliverables:

Q.  What types of end products can be derived from LiDAR point clouds?
A. Products that can be developed from a LiDAR point cloud include, but not limited to: bare-earth digital elevation models, triangulated irregular networks, high profile contours, 3D animations, 3D renderings, complete planimetrics (2D or 3D drawings), and colorized point clouds, among others.

Q. In what formats can LiDAR data be delivered?
A. LiDAR data can be delivered in many formats including: point clouds in the form of LAS files or ASCII files (colorized point cloud); vector data in the form of a DGN, DWG, KML/KMZ, TIN, shapefile, or geodatabase; and raster data in the form of DTM’s.

Q. How does LiDAR data differ from traditional surveying data in terms of end products?
A. With Mobile LiDAR scanning, complete scenes (in 3D) are captured and blanketed with high-density scan information in fine detail because the system is literally able to capture millions of points during each collection. An added bonus is the simultaneous collection of photography that depicts the objects within the point cloud. Time is saved by capturing the entire project the first time and preventing costly go-backs. With traditional surveying, there are substantially less points captured, causing the need to “connect the dots” to obtain linear features during post-processing, and significantly reduced overall scene comprehension

Additional Information and Contacts:

Q. Who can I contact for further information regarding project scope, project deliverables and project pricing?

A. Baker has a team of Mobile LiDAR professionals that are ready to assist you with any questions you may have. Please feel free to contact any of our Team listed on the "About Us" page.