2012 Coastal California 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 1.0m

using seven Cessna 441 aircrafts flying at an average

flight height of 9052m AGL. All aircraft flew with

Leica Geosystem's ADS80/SH82 digital sensors with

firmware 3.20 or newer. Each sensor collected 11

image bands. PanF27A,PanF02A and PanB14A panchromatic

bands with a spectral range of 465-676nm. RedN00a and

RedB16a with a spectral range of 604-664nm. GrnN00a

and GrnB16a with a spectral range of 533-587nm.

BluN00a and BluB16a with a spectral range of 420-492nm

and Near-infrared bands NirN00a and NirB16a with a

spectral range of 833-920nm. The CCD arrays have a

pixel size of 6.5 microns in a 12000x1 format. Both

the CCD's and the A/D convertors have a dynamic

range of 12bits. The data is stored in 16bit format.

The ADS is a push-broom sensor and the ground

footprint of the imagery at NAIP scale is 12km wide

by the length flightline. The maximum flightline

length is limited to approximately 240km.

The factory calibrations and IMU alignments for each

sensor (Serial Numbers: 1321, 30011, 30012, 30014,

30017, 30022, 30034, and 30103) were tested and

verified by in-situ test flights before the start

of the project. The Leica ADS Flight Planning and

Evaluation Software (FPES) 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 FPES

for flight line design. The design parameters used in

FPES will be 30% lateral overlap and 1.0m resolution.

The flight lines have been designed with a north/south

orientation. 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 FPES design to ensure the 1m 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). Technicians precisely measured tie

points in 3 bands/looks (Back/Nadir/Forward) for each

line using Leica Xpro software. The resulting point

data and exterior orientation data were used to

perform a full bundle adjustment with 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 April

2012 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 4.6

package which was used for the final radiometric

balance, mosaic, and DOQQ sheet creation of the final

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

resolution of 1m.