Photogrammetrics

Purpose

The Photogrammetric Unit produces accurate geospatial products used for planning, designing, constructing, and maintaining Minnesota’s Trunk Highway System. This unit specializes in aerial imagery, Light Detection and Ranging (LiDAR), and the operation of Unmanned Aircraft Systems (UAS) for precision mapping.

When to use this subject

If you need topographic information and it is impractical to perform a field survey due to constraints such as size, hazardous conditions, or access limitations.

Common instances include:

Areas where high-resolution imagery is needed
There will be new construction or improvements to existing infrastructure
UAS operations for small projects that require precision mapping and would be difficult to survey using traditional methods
Americans with Disability Act (ADA) Digital Terrain Model (DTM) and feature extraction
As-built data
Questions about imagery, LiDAR, or drones
Accuracy of the data and products produced by the Photogrammetric Unit

How this subject fits into the overall project development process

Photogrammetric mapping is one of the first steps in the construction program. The products are used from scoping all the way through final design and sometimes post construction
Photogrammetric data is typically requested at least 4 years before the project letting date
All photogrammetric project requests are channeled through District Survey offices
Aerial imagery and LiDAR are collected twice a year. During the spring after snow melt but before the leaves come out and in the fall after the leaves are off but before snowfall
Lead time for photogrammetric projects is a minimum of 6 months from the time of imagery/LiDAR acquisition

Organizations involved

MnDOT:

District Surveying
District Design
Foundations Unit (Geotechnical Engineering Section)
Office of Aeronautics
Office of Environmental Stewardship
Facilities Management

Municipalities and counties