oktibbeha.sid

This data has been produced to be fully compliant with the

National Standard for Spatial Data Accuracy (NSSDA) at

a scale of 1 to 400 with a 2' GSD.

The aerial imagery acquisition for the Mississippi

Statewide project (Part A) was flown to support the

creation of digital orthophotography with a 2' GSD. The

imagery was acquired in 31 lifts consisting of 285 lines

running east, west. The imagery was flown at 18,900 feet

above mean terrain.  Imagery was flown with a  30%

overlap between flight lines.  All imagery was collected

using the Leica ADS40 digital pushbroom sensor.

Waggoner Engineering, Inc., under contract to EarthData

International, Inc. successfully established ground control

for the Mississippi Statewide project (Part A).  A total of 43

ground control points in Mississippi  were acquired using

GPS for both vertical and horizontal coordinate values.  All

43 points utilized photo identifiable points.

The U.S. Geological Survey has developed a National

Elevation Dataset (NED). The NED is a seamless mosaic

of best-available elevation data. The 7.5-minute elevation

data for the conterminous United States are the primary

initial source data. In addition to the availability of

complete 7.5-minute data, efficient processing methods

were developed to filter production artifacts in the existing

data, convert to the NAD83 datum, edge-match, and fill

slivers of missing data at quadrangle seams. One of the

effects of the NED processing steps is a much-improved

base of elevation data for calculating slope and

hydrologic derivatives. The specifications for the NED

Geographic coordinate system Horizontal

datum of NAD83, Vertical datum of NAVD88, units of

meters.

EarthData utilized an ISTAR workflow for processing the

aerotriangulation (AT) for the orthoimagery covering the

Mississippi Statewide project area (Part A).  The airborne

GPS data was processed and integrated with the inertial

measurement unit (IMU). The resulting imagery and

control were imported into the ISTAR system for use in the

aerotriangulation. The ADS40 imagery was downloaded

onto the EarthData server and brought over to the UNIX

based ISTAR system. The ground control was used in

conjunction with the processed airborne global

positioning system (ABGPS) results for the AT.  A total of 6

surveyed ground control points were not used (HV_B04 -

This point was used only for elevation due to a possible

survey error.  HV_C01 - Point could not be measured

because the stop bar blended into the dirt.  HV_C02 - Not

used because there were trees covering the point.

HV_C04 - Not used because there were trees covering

the point.  HV_C05 - The newly poured concrete walkway

surveyed was not there at the time of the flight.  HV_D03 -

Point could not be accurately measured due to building

lean and the shadows from the building.).  A total of 13

surveyed ground control points from previous 6" GSD

projects were used (Tippah County, MS - 6 points;

Lauderdale County, MS - 2 points; Clay County, MS - 5

points). The ground control points were read in all

available imagery and tie points between flight lines were

selected.  A fully analytical bundle adjustment was run.

The properly formatted ISTAR results were used for

subsequent processing.  All final results were output into

an AT report.

The AT for the Mississippi Statewide project (Part A) was

completed by block.  Part A consisted of 3 blocks.  Block

1 AT was completed on 10/5/06.  Block 2 AT was

completed on 10/6/06.  Block 3 AT was completed on

10/16/06.

The NED was downloaded from the USGS website.

Using the DEM data set, the technician verified that there

were no voids, and that the data covered the project limits.

The technician then selected a series of areas from the

dataset and inspected them where adjacent flight lines

met.  Ground control point checks were performed on the

NED to ensure the accuracy specifications were met.

This DEM surface is used in the rectification of the

orthoimagery.

The DEM for the Mississippi Statewide project (Part A)

was completed by block.  Part A consisted of 3 blocks.

Block 1 was completed on 11/16/06.  Block 2 was

completed on 11/7/06.  Block 3 was completed on

12/13/06.

The digital orthophotography is comprised of a 24 bit,

natural color, 2' GSD ground orthos for the Mississippi

Statewide project (Part A).  The ISTAR process was used

in the generation of the orthoimagery covering the

Mississippi Statewide project (Part A).  The initial

radiometric adjustments were performed on the imagery

for each flight line attempting to reach the best possible

histogram. The rectification process was then run using

the DEM surface and the radiometrically

balanced imagery on each flight line. The quicklook

(reduced resolution rectification) of each flight line

exported out of ISTAR.  A second set of radiometric

adjustments were made using EarthData proprietary

tools. The radiometrically balanced imagery was then

re-imported into the ISTAR system and the histogram from

the quicklook was applied to the full resolution imagery.

Mosaic lines were placed, joining the ADS40 imagery

strips. An initial QA/QC was performed by the technician to

ensure that the mosaic lines were appropriately placed

and that there was appropriate imagery coverage. The

final imagery data set is removed from the ISTAR

environment in a process called "packaging" where the

individual tiles are created.  It is during packaging that final

datum and projection are defined (Mississippi State Plane

East, NAD83/HARN, NAVD88, US Survey Feet).  The

created tiles are reviewed again for anomalies and

interactive radiometric adjustment applied where needed.

QA/QC was performed looking for anomalies, smears

and other indications of problems within the digital

orthophoto creation process, interactive

radiometric adjustment applied where needed. Two

additional radiometric adjustments are applied to the

completed orthos in Adobe Photoshop. The first is a

sharpening mask filter; this filter is used to help increase

sharpness of a digital image.  The basis for this filter is to

locate pixels that differ in value from surrounding pixels by

the threshold specified. It then increases the pixels'

contrast by the value identified. For neighboring pixels

specified by the threshold, the lighter pixels get even

lighter and the darker pixels get even darker based on the

specified amount. The changes made maintained the

integrity of the original histogram curve.  The final digital

ortho product was GeoTIFF with TFW and a seamless

mosaic for each county.  All data was delivered on

firewire.

The digital orthophotos for the Mississippi Statewide

project (Part A) was completed by block.  Part A consisted

of 3 blocks.  Block 1 was completd on 1/30/07.  Block 2

was completed on 12/20/06.  Block 3 is

scheduled to be completed by 2/27/07.

Metadata imported.