2017 Coastal Washington NAIP 4-Band 8 Bit Imagery

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Digital Georectified Image. | Source Geospatial Form: remote-sensing image | Type of Source Media: UnKnown

Digital imagery was collected at a nominal GSD of

40cm using nine Cessna 441, one Reims F406, one Piper and

one Merlin aircraft flying at an average flight height of

8400m AGL for the SH120 acquisition and 4400m AGL for

SH100 acquisition. Aircraft flew with Leica Geosystem's

ADS100/SH100 digital sensors with firmware 4.57 or

ADS100/SH120 digital sensors with firmware 4.57. Each

sensor collected 12 image bands Red,Green,Blue and

Near-infrared at each of three look angles; Backward 19

degrees, Forward 26 degrees and Nadir for the SH100.

Backward 10 degrees, Forward 14 degrees, and Nadir for

the SH120. The Nadir Green band was collected in high

resolution mode effectively doubling the resolution for

that band. The ADS100 spectral ranges are; Red 619-651nm,

Green 525-585nm, Blue 435-495nm and Near-infrared at

808-882nm. The CCD arrays have a pixel size of 5.0 microns

in a 20000x1 format at nadir; a 18000x1 format at the

backward look angle and a 16000x1 format at the forward

look angle. The CCD's have a dynamic range of 72db and

the A/D converters have a resolution of 14bits. The ADS

is a push-broom sensor the ground footprint of the imagery

is approximately 8km wide at a nominal 40cm GSD by the

length flightline. The maximum flightline length is limited

to approximately 175km. The factory calibrations and IMU

alignments for each sensor (Serial Numbers: 10511,10512,

10514,10522,10527,10530,10531,10534,10540,10554,12502)

were tested and verified by in-situ test flights before

the start of the project. The Leica MissionPro Flight

Planning Software is used to develop the flight acquisition

plans. Flight acquisition sub blocks are designed first to

define the GNSS base station logistics, and to break

the project up into manageable acquisition units. The

flight acquisition sub blocks are designed based on

the specified acquisition season, native UTM zone of

the DOQQs, flight line length limitations (to ensure

sufficient performance of the IMU solution) as well

as air traffic restrictions in the area. Once the sub

blocks have been delineated they are brought into

MissionPro for flight line design. The design

parameters used in MissionPro will be 30% lateral

overlap and 40cm resolution.

The flight lines

have been designed with a north/south orientation or

east/west where required for efficiency.

The design takes into account the latitude of the

state, which affects line spacing due to convergence

as well as the terrain. SRTM elevation data is

used in the MissionPro design to ensure the 50cm

GSD is achieved over all types of terrain. The raw

data was downloaded from the sensors after each

flight using Leica XPro software. The imagery was

then georeferenced using the 200Hz GPS/INS data

creating an exterior orientation for each scan line

(x/y/z/o/p/k). Leica Xpro APM software was used to

automatically generate tiepoint measurements between

the forward, nadir and backward look angles for each line

and to tie all flight lines together. The resulting point

data and exterior orientation data were used to perform

a full bundle adjustment using ORIMA software. Blunders

were removed, and additional tie points measured in weak

areas to ensure a robust solution. Once the point data

was clean and point coverage was acceptable,

photo-identifiable GPS-surveyed ground control points

were introduced into the block adjustment. The bundle

adjustment process produces revised exterior orientation

data for the sensor with GPS/INS, datum, and sensor

calibration errors modeled and removed. Using the

revised exterior orientation from the bundle adjustment,

orthorectified image strips were created with Xpro

software and the June 2014 USGS 10m NED DEM. The Xpro

orthorectification software applies an atmospheric-BRDF

radiometric correction to the imagery. This correction

compensates for atmospheric absorption, solar

illumination angle and bi-directional reflectance. The

orthorectified strips were then overlaid with each other

and the ground control to check accuracy. Once the accuracy

of the orthorectified image strips were validated the

strips were then imported into Inpho's OrthoVista 7.0

package which was used for the final radiometric

balance, mosaic, and DOQQ sheet creation. The final

DOQQ sheets, with a 300m buffer and a ground pixel

resolution of 1m or 60cm were then combined and compressed

to create the county wide CCMs