Spatial Resolution
Spatial resolution determines the smallest feature visible within a region of an image. Although commonly defined in terms of the Ground Sample Distance (GSD), it is also strongly influenced by the Point Spread Function (PSF) or 2-D image blur and noise. Image blur is often specified as a single parameter such as the Modulation Transfer Function (MTF) at the Nyquist frequency or, more simply, as Relative Edge Response (RER).
Laboratory Measurements
I2R performs laboratory assessments of spatial resolution using a tilted edge technique. Assessments are done in two directions.
I2R provides customers with quantified spatial resolution measures including:
Modulation Transfer Function (MTF) curves
MTF at the Nyquist frequency
Line Spread Function (LSF)
Relative Edge Response (RER)
In-flight Spatial Resolution
I2R provides image quality assessment to clients as services or customized tools and software.
Two Approaches:
Image traditional Engineered Targets
Can be high quality but limited availability of targets
Hard to maintain
Image naturally occurring in-scene edges
Automated technique finding and using a large number of edges - Spatial Resolution Image Quality Estimation - (SR-IQE)
Engineered Targets
I2R designs and builds custom engineered targets for clients.
Common engineered target types:
Point Source Targets
Arrays of convex mirrors
Single night lights
Contrast Transfer Function (CTF) Targets
Multibar and tri-bar
Siemens star radial targets
Edge/Pulse Targets
Checkerboard and other edge targets
Pulse targets
Spatial Resolution Image Quality Estimation Tool (SR-IQE)
I2R offers an image quality assessment service using our Spatial Resolution Image Quality Estimation tool - SR-IQE. In-flight imagery over urban features or other edge-rich scenes is used to quantify image quality. The technique does not require special imagery acquired over predetermined targets, and can accept all standard image file formats. SR-IQE has been extensively validated against industry standard methods and engineered targets funded by NASA and DHS.
Potential users of SR-IQE Spatial services are sensor and image providers who want to monitor or validate in-flight performance, organizations that purchase high to moderate resolution remotely sensed imagery, software developers interested in optimizing image restoration algorithms, and intelligence agencies interested in automated NIIRS estimation.
By statistically examining imagery acquired over urban environments that contain roads, buildings and other edge features, I2R Provides customers with:
Quantified spatial resolution measures including: Modulation Transfer Function (MTF) curves, MTF at the Nyquist frequency, MTF at half the Nyquist frequency and Relative Edge Response (RER) in the in-track and cross track direction.
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