Article By Jodi Boe

GK Technology, Inc. is excited to share that we have gained access to the 2021 lidar data for the Red River Valley region of Minnesota. We understand how important it is to have access to the most up-to-date lidar data for building surface drainage and tile maps and for validating management zones.

This new lidar is brought to us by the Red River Watershed Management Board (RRWMB), who have provided us with access to this lidar data. We are grateful for their partnership and are excited to bring this powerful resource directly to your fingertips through the ADMS Consultants package.

Important Notes on Using RRWMB Lidar Data

As part of the agreement with the RRWMB, any maps that you create using RRWMB lidar data must include the information in the image below. A PDF version of this picture is also attached and can be added to the end of a PDF stack or printed and added to paper copies of maps. Only lidar data supplied by the RRWMB needs to include this statement. RRWMB lidar data is clearly identified in the ADMS Lidar Library by County 2021RRWMB (see example to the right). Your cooperation in adding the below statement ensures that we can continue to provide valuable data such as this into the future.

This statement does NOT affect any other data included in the ADMS Consultants package. You only need to include the above statement IF you use RRWMB lidar data obtained within the ADMS Consultants package.  LINK TO RRWMB LEGAL STATEMENT

Further, you may notice that it is taking a little longer to process RRWMB lidar data than other lidar data used in the past. Typically, when we host lidar data on our servers, we reproject the raw lidar data, thin, and zip it, changing it from an LAS file to a LAZ file, resulting in a file size that is reduced by 10 to 15 times. This maximizes storage space while maintaining data integrity and increases request speed, meaning it takes a shorter amount of time to get the lidar data you need when you want it. To meet our use agreement with RRWMB, we cannot modify the lidar data files before hosting it on our server so the file size of RRWMB lidar is around 25 TB, versus 2 TB, meaning that ADMS spends more time searching for the correct lidar files when a RRWMB lidar tile is requested from the server. If you get a timeout while trying to download RRWMB lidar data or the lidar data just doesn’t come in after your request, hit OK to the timeout error and click the download button again right away.

Processing RRWMB Lidar Data

GK Technology employees have been using the new lidar data from RRWMB and have noticed some important issues that you should be aware of. There are fields scattered around the RRV that where greener, or heavier vegetation than normal, for the time of the year that lidar was flown in 2021. Lidar uses NIR (Near Infra-Red) light pulses that hit the earth and return to a sensor. All light pulses that hit the earth and return to the sensor are classified into the groups shown on the right, the same boxes shown in ADMS when pulling lidar data from the GK Server. GK suggests selecting “Synthetic (Mass Point),” “Ground,” and “Water” hits (this is the default in ADMS).  

Since some of the fields were “Greener” than normal when lidar was flown in 2021, “Ground” hits may not have penetrated the canopy. Shown below is a very heavy vegetation sugar beet field (notice the pre-pile openings and ditch bottoms). Adding in other options or classifications can fill in the voids. From our testing, the elevations are obviously raised. GK suggests using the 2008 lidar data at this time if you come across a similar situation.

Future Lidar Additions to GK Server

A new lidar flight for the MN RRV is scheduled for 2024 or 2025. This data will be collected by the State of Minnesota and USGS. This is something to keep in mind for anyone with upcoming topographic projects. Minnesota and USGS have been publishing state-flown lidar data at a brisk pace and we at GK plan to host the newest lidar data on our Server as fast as we can.

GK Technology is thankful to all the agencies that have pulled together not only lidar data but all of the data that is available on the GK Server for our Consultants Users. We hope that access to this new data helps you grow your business. If you have any questions, please contact our office at 855-458-3244. Thank you.