Imagery FAQ

What kind of imagery does the State obtain?

 

The State of Maryland generally obtains two imagery products:

  • 6 inch High Resolution leaf-off imagery
  • 1-meter National Agriculture Imagery Program (NAIP) leaf-on imagery.

How does the State obtain imagery?

 

High Resolution 6 Inch Imagery
The Maryland Department of Information Technology (DoIT) has executed a Digital High-Resolution Aerial Photography Contract through the CATS+ contracting vehicle.

NAIP Imagery
The one-meter leaf on imagery is obtained from the USDA Farm Service Agency - National Agriculture Imagery Program (NAIP). The State purchases the NAIP imagery from USDA.

How often does the State obtain imagery?

 

State of Maryland imagery collection cycle is as follows:

6 Inch High Resolution Imagery
Imagery is obtained in three year cycles.

  • Year 1: Eastern Shore
  • Year 2: Western Shore
  • Year 3: Off-Year/No Collection
 
NAIP Imagery
The NAIP imagery for Maryland is collected by the USDA every other year on the odd years.

Can local jurisdictions use the Digital High-Resolution Aerial Photography contract?

 

Yes, local jurisdictions can use this contract to obtain aerial photography or other buy-ups.  The buy-ups include:

  • Orthophotography (up to 3 inch resolution)
  • LiDAR Data
  • Oblique Imagery
  • Planimetrics
  • Land Use/Land Cover Updates
Please visit the Imagery buy-ups options page to learn more about these products and how to get pricing.

Why doesn’t the State obtain the imagery more often?

 

The high-resolution imagery is always obtained during leaf-off periods.  The collection is done during this time because the imagery program is primarily funded by the Maryland Emergency Numbers System Board and therefore supports emergency response efforts.  Leaf-off imagery allows for more effective coordination and response efforts when used by the local jurisdiction public safety answering points.  There is also an extensive review process done by the local jurisdictions to ensure quality control of the products.

How can I get the imagery?

 

MD iMAP offers the imagery as a variety of services and raw data downloads.  We offer both Map and Image services of the latest imagery.  Historic imagery services are also available.  Please visit our Imagery Downloads page to explore the different ways you can obtain the raw imagery.

What can I do with the Image Service?

 

An image service allows the user to access any attributes associated with the imagery, you can query and identify.  You can also use the image service to manipulate the color bands to switch to products such as Color Infrared.

Can I use the imagery outside of the ArcGIS platform?

 

Yes, the imagery has the web map service (WMS) capability enabled. A WMS service makes the imagery available across different platforms and clients. Any client built to support WMS can view and work with the service.

What are the accuracy specifications of the imagery?

 

High-Resolution Imagery
Aerial imagery is currently required to meet American Society for Photogrammetry and Remote Sensing (ASPRS) Class I Accuracy Standards for 1" =200' maps. The base product is collected at a 6 inch ground pixel resolution with a horizontal accuracy of 4.895 feet. The current specifications also require the imagery shall be 4-band (Red, Green, Blue, and Near-Infrared) and leaf-off.

NAIP Imagery
NAIP imagery is acquired at a one-meter ground sample distance (GSD) with a horizontal accuracy that matches within six meters of photo-identifiable ground control points, which are used during imagery inspection.

The default spectral resolution is natural color (Red, Green and Blue, or RGB) but beginning in 2007, Maryland has been delivered with four bands of data: RGB and near infrared.