Integrating knowledge, technology & data into working systems

Project OverviewProject Overview

GISDATA D.O.O. Ivana Lampek Pavčnik,

ivana.lampek@gisdata.hr

COMPARISON COMPARISON BETWEEN AERIAL DIGITAL BETWEEN AERIAL DIGITAL ORTHOPHOTO AND ORTHOPHOTO AND SATELLITE SATELLITE IMAGESIMAGES

Project GoalsProject Goals

COMPARISON:– Quality of geometrical corrections– Quality of Interpretability – Time for defining and ordering– Time for geometric correction– Price

DescriptionDescription

The focus of the project was to examine the results of different type comparisons and discuss the advantages or disavantages between aerial and satellite images

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See the final report and procesed data

Data used in projectData used in project

Aerial black/white photos – Area of interest: city Karlovac and

environment– Area: 42000 m2– Scale of expose: 1:20000– Number of frames: 10, spatial resolution=0,5m– Date:

• For the frame 317: 04. 05. 2000.• For the frame 2/1: 29. 02. 2000

Data used in projectData used in project

Color aerial photos – Area of interest: city Karlovac and

environment– Area: 27000 m2– Scale of expose: 1:20000– Number of frames: 6, spatial resolution=0,5m– Date:

• May, 2002.

Data used in projectData used in project

IKONOS satellite images – Area of interest: city Karlovac and

environment– Area: 57 000 m2– Number of frames: 2, spatial resolution=1m– Date:

• May, 2003.

TechnologyTechnology

Digital Photogrammetry for geometrical corrections

Digital PhotogrammetryDigital PhotogrammetryGoal: Creating OrthosMeans

– Aerial Triangulation– Orthorectification

Why ORTHOrectify?Why ORTHOrectify?

There are geometric errors associated with satellite images and aerial photographs

Errors are caused by:– Scale Variation– Sensor Attitude/Orientation– Internal Sensor Errors

Orthorectification removes these errors

Scale VariationScale Variation

2 cm

Scale varies across the photography

6 cm

House width = 8m

Scale is 1:400

Scale is 1:133

Scale VariationScale Variation

House width constant (8m), width in photographs varies, therefore scale varies

Differences between aerial Differences between aerial triangulationstriangulations

Aerial photos> to establish Image Coordinates

Provided in a Camera Calibration Certificate Parameters defining this geometry are:

– Focal length– Radial Lens Distortion– Principal Point– Fiducial Coordinates

Optical Axis

Image/Focal Plane

Focal Length

Internal Geometry of satelliteInternal Geometry of satellite

Usually the internal parameters are read from the image header (SPOT, IRS):– Focal length– Principal point Xo, Yo– Pixel Size– Number of sensor Columns

In the IKONOS and Quick Bird case, the geometry is modeled using rational polynomials

User does not need to define these

Flight Line Characteristics for aerial Flight Line Characteristics for aerial photosphotos

A block should have at least one pair of images that overlap

IKONOS or Quick Bird images do not need to have at least one pair of images that overlap

Acquiring Ground GCP Acquiring Ground GCP CoordinatesCoordinates

Coordinates of GCPs in external orientation can be gathered using various techniques:– Using GPS– From Maps– From other rectified imagery

Should have X, Y and Z values for overlapping aerial images

Should have X, Y for satellite images and Z values from DEM

The Influence of Quality EstimatesThe Influence of Quality Estimates

Ground

Image

InputtedStandard Deviations(Measures of Quality)

Adjustment process will move points until the “best solution” is found

The points fluctuate with weighted limits as specified by the standard deviation valuesAdjustment takes

places in the X, Y AND Z direction

Block ResidualsBlock Residuals

• There are RESIDUALS for:- Each ground point- Each image point- Each perspective center

• Block of eight images…

• Least Squares Adjustment calculates new points based on distributing and minimizing residuals throughout the ENTIRE block

• Image & ground measurements

Color Aerial images:– mX mY mZ

0.3239 0.309 0.6507B&W Aerial images :

– mX mY mZ

0.4175 0.4641 0.4220

IKONOS:

mX mY mZ0.3879 0.3687 DEM -accuracy

Block Residuals for all data sourcesBlock Residuals for all data sources

RESULTS of geometrical RESULTS of geometrical correction:correction:

1

2

4

31. Pixel in the DEM (Height)

2. Parameters of Interior and Exterior Orientation

3. In the image, a brightness value is determined based on the resampling of surrounding pixels

4. Height, Interior and Exterior Orientation information and Brightness Value are used to calculate equivalent location in the Ortho Image

The orthographic image is constructed by resampling the original image pixels into their new orthorectified positions

Orthographic Projection

Digital terrain model:Digital terrain model:

- 32 digitized maps with scale 1: 5000- equidistance: 5m-summary: 125 878 arcova for generating the surface model

Digital orthophotosDigital orthophotos

CORRECTED Images as result of ortorectification process

The software takes each DEM pixel and finds the equivalent position in the image. A brightness value is calculated based on the surrounding pixels. This brightness value, the elevation, the interior orientation and exterior orientation information is used to calculate the equivalent location on the ortho image

Quality of interpretabilityQuality of interpretability

Automatic interpretationDefining the level of

Image Interpretability Rating Scales

Automatic interpretationAutomatic interpretation

Seed properties>

Neighborhood: This option determines which pixels will be considered contiguous to the seed pixel. Any neighbor pixel that meets all selection criteria is accepted and thus, itself, becomes a seed pixel.        If four neighbors are searched, then only those pixels above, below, to the left, and to the right of the seed pixel are considered contiguous.        If eight neighbors are searched then the diagonal pixels are also considered contiguous.Geographic Constraints: This group allows you to enter constraints for the AOI. You can select only one option or use both options.Area: The maximum size of the AOI Distance: specifying a distance from the seed pixel. Spectral Euclidean Distance: The Euclidean spectral distance in digital number (DN) units on which to accept pixels. The pixels that are accepted will be within this spectral distance from the mean of the seed pixel.

SED= 10, AREA=5000 pixels SED= 49, AREA=5000 pixels

SED= 50, AREA=5000pixels

SED= 10, AREA=5000 pixels

SED= 13, AREA=5000 pixels

SED= 10, AREA=5000 p

UNSUPERVISED CLASSIFICATIONUNSUPERVISED CLASSIFICATION ISODATA algorithm to perform an unsupervised

classification. ISODATA stands for "Iterative Self-Organizing Data Analysis Technique.“

It is iterative in that it repeatedly performs an entire

classification (outputting a thematic raster layer) and recalculates statistics. "Self-Organizing" refers to the way in which it locates the clusters that are inherent in the data.

The ISODATA clustering method uses the minimum spectral distance formula to form clusters. It begins with either arbitrary cluster means or means of an existing signature set, and each time the clustering repeats, the means of these clusters are shifted. The new cluster means are used for the next iteration.

UNSUPERVISED UNSUPERVISED CLASSIFICATIONCLASSIFICATION The ISODATA utility

repeats the clustering of the image until either:– a maximum number of

iterations has been performed, or

– a maximum percentage of unchanged pixels has been reached between two iterations.

Identification of agriculture

Identification of forest

Interpretation into 20 categoryInterpretation into 20 category

IKONOS imageIKONOS image Aerial color imageAerial color image

Defining the level of Defining the level of Image Interpretability Rating ScalesImage Interpretability Rating Scales National Imagery Interpretability Rating

Scale (NIIRS) >– to define and measure the quality of images

and performance of imaging systems – NIIRS has been primarily applied in the

evaluation of aerial imagery, it provides a systematic approach to measuring the quality of photographic or digital imagery, the performance of image capture devices, and the effects of image processing algorithms.

NIIRS 5 [0.75 - 1.2 m GRD]

1m IKONOS images, aerial images 1:40000 i s.r. 21-28μm

Output scale 1:5000VisibleVisible

NIIRS NIIRS RadarRadar

NIIRS NIIRS InfraredInfrared

NIIRS NIIRS MultispectralMultispectral

NIIRS NIIRS

Distinguish between a Distinguish between a MIDAS and a MIDAS and a CANDID by the CANDID by the presence of refueling presence of refueling equipment (e.g., equipment (e.g., pedestal and wing pedestal and wing pod). pod).

Identify radar as vehicle-Identify radar as vehicle-mounted or trailer-mounted or trailer-mounted. mounted.

Identify, by type, deployed Identify, by type, deployed tactical SSM systems tactical SSM systems (e.g., FROG, SS-21, (e.g., FROG, SS-21, SCUD). SCUD).

Distinguish between SS-25 Distinguish between SS-25 mobile missile TEL mobile missile TEL and Missile Support and Missile Support Vans (MSVS) in a Vans (MSVS) in a known support base, known support base, when not covered by when not covered by camouflage. camouflage.

Identify TOP STEER or Identify TOP STEER or TOP SAIL air TOP SAIL air surveillance radar on surveillance radar on KIROV-, KIROV-, SOVREMENNY-, SOVREMENNY-, KIEV-, SLAVA-, KIEV-, SLAVA-, MOSKVA-, KARA-, MOSKVA-, KARA-, or KRESTA-II-class or KRESTA-II-class vessels.vessels.

Count all medium Count all medium helicopters (e.g., helicopters (e.g., HIND, HIP, HAZE, HIND, HIP, HAZE, HOUND, PUMA, HOUND, PUMA, WASP). WASP).

Detect deployed TWIN Detect deployed TWIN EAR antenna. EAR antenna.

Distinguish between river Distinguish between river crossing equipment crossing equipment and medium/heavy and medium/heavy armored vehicles by armored vehicles by size and shape (e.g., size and shape (e.g., MTU-20 vs. T-62 MTU-20 vs. T-62 MBT). MBT).

Detect missile support Detect missile support equipment at an SS-25 equipment at an SS-25 RTP (e.g., TEL, RTP (e.g., TEL, MSV). MSV).

Distinguish bow shape and Distinguish bow shape and length/width length/width differences of SSNS. differences of SSNS.

Detect the break between Detect the break between railcars (count railcars (count railcars).railcars).

Distinguish between single-Distinguish between single-tail (e.g., FLOGGER, tail (e.g., FLOGGER, F-16, TORNADO) and F-16, TORNADO) and twin-tailed (e.g., F-15, twin-tailed (e.g., F-15, FLANKER, FLANKER, FOXBAT) fighters. FOXBAT) fighters.

Identify outdoor tennis Identify outdoor tennis courts. courts.

Identify the metal lattice Identify the metal lattice structure of large (e.g. structure of large (e.g. approximately 75 approximately 75 meter) radio relay meter) radio relay towers. towers.

Detect armored vehicles in a Detect armored vehicles in a revetment. revetment.

Detect a deployed TET Detect a deployed TET (transportable (transportable electronics tower) at electronics tower) at an SA-10 site. an SA-10 site.

Identify the stack shape Identify the stack shape (e.g., square, round, (e.g., square, round, oval) on large (e.g., oval) on large (e.g., greater than 200 greater than 200 meter) merchant ships.meter) merchant ships.

Detect automobile in a Detect automobile in a parking lot. parking lot.

Identify beach terrain Identify beach terrain suitable for suitable for amphibious landing amphibious landing operation. operation.

Detect ditch irrigation of Detect ditch irrigation of beet fields. beet fields.

Detect disruptive or Detect disruptive or deceptive use of paints deceptive use of paints or coatings on or coatings on buildings/structures at buildings/structures at a ground forces a ground forces installation. installation.

Detect raw construction Detect raw construction materials in ground materials in ground forces deployment forces deployment areas (e.g., timber, areas (e.g., timber, sand, gravel).sand, gravel).

NIIRS 6 [0.40 - 0.75 m GRD]

0,58 m QUICK BIRD images, aerial photos 1:20000 i 14-28μm

Output scale: 1:2000VisibleVisible

NIIRS NIIRS RadarRadar

NIIRS NIIRS InfraredInfrared

NIIRS NIIRS MultispectralMultispectral

NIIRS NIIRS

Distinguish between models Distinguish between models of small/medium of small/medium helicopters (e.g., helicopters (e.g., HELIX A from HELIX A from HELIX B from HELIX B from HELIX C, HIND D HELIX C, HIND D from HIND E, HAZE from HIND E, HAZE A from HAZE B from A from HAZE B from HAZE C). HAZE C).

Identify the shape of Identify the shape of antennas on antennas on EW/GCI/ACQ radars EW/GCI/ACQ radars as parabolic, parabolic as parabolic, parabolic with clipped comers or with clipped comers or rectangular. rectangular.

Identify the spare tire on a Identify the spare tire on a medium-sized truck. medium-sized truck.

Distinguish between SA-6, Distinguish between SA-6, SA- I 1, and SA- 17 SA- I 1, and SA- 17 missile airframes. missile airframes.

Identify individual launcher Identify individual launcher covers (8) of vertically covers (8) of vertically launched SA-N-6 on launched SA-N-6 on SLAVA-class vessels. SLAVA-class vessels.

Identify automobiles asIdentify automobiles as

Distinguish between Distinguish between variable and fixed-variable and fixed-wing fighter aircraft wing fighter aircraft (e.g., FENCER vs. (e.g., FENCER vs. FLANKER). FLANKER).

Distinguish between the Distinguish between the BAR LOCK and SIDE BAR LOCK and SIDE NET antennas at a NET antennas at a BAR LOCK/SIDE BAR LOCK/SIDE NET acquisition radar NET acquisition radar site. site.

Distinguish between small Distinguish between small support vehicles (e.g., support vehicles (e.g., UAZ-69, UAZ-469) UAZ-69, UAZ-469) and tanks (e.g., T-72, and tanks (e.g., T-72, T-80). T-80).

Identify SS-24 launch triplet Identify SS-24 launch triplet at a known location. at a known location.

Distinguish between the Distinguish between the raised helicopter deck raised helicopter deck on a KRESTA II (CG) on a KRESTA II (CG) and the helicopter deck and the helicopter deck with main deck on a with main deck on a KRESTA I (CG). KRESTA I (CG).

Detect wing-mounted stores Detect wing-mounted stores (i.e., ASM, bombs) (i.e., ASM, bombs) protruding from the protruding from the wings of large wings of large bombers (e.g., B-52, bombers (e.g., B-52, BEAR, Badger). BEAR, Badger).

Identify individual thermally Identify individual thermally active engine vents active engine vents atop diesel atop diesel locomotives. locomotives.

Distinguish between a FIX Distinguish between a FIX FOUR and FIX SIX FOUR and FIX SIX site based on antenna site based on antenna pattern and spacing. pattern and spacing.

Distinguish between Distinguish between thermally active tanks thermally active tanks and APCs. and APCs.

Distinguish between a 2-rail Distinguish between a 2-rail and 4-rail SA-3 and 4-rail SA-3 launcher. launcher.

Identify missile tube hatches Identify missile tube hatches on submarines. on submarines.

Detect summer woodland Detect summer woodland camouflage netting camouflage netting large enough to cover large enough to cover a tank against a a tank against a scattered tree scattered tree background. background.

Detect foot trail through tall Detect foot trail through tall grass. grass.

Detect navigational channel Detect navigational channel markers and mooring markers and mooring buoys in water. buoys in water.

Detect livestock in open but Detect livestock in open but fenced areas. fenced areas.

Detect recently installed Detect recently installed minefields in ground minefields in ground forces deployment area forces deployment area based on a regular based on a regular pattern of disturbed pattern of disturbed earth or vegetation. earth or vegetation.

Count individual dwellings Count individual dwellings in subsistence housing in subsistence housing areas (e.g., squatter areas (e.g., squatter settlements, refugee settlements, refugee camps). camps).

Time for defining and orderingTime for defining and ordering

Aerial images in archive: 10-15days

IKONOS in archive: 10-15days– Min.order=100km2

Quick Bird in archive: 10-15days– Min.order=64km2

Time for geometric correctionTime for geometric correction Triangulation:

– Aerial (10 frames)=2,5 days– IKONOS (2 frames)= 1 day

Ortorectification: the same Color matching and mosaic:

– Aerial b/w (10 frames)=3 days– Aerial color (10 frames)=4 days– IKONOS color (2 frames) =1 day

Summary:Summary:Aerial Aerial colorcolor : 7,5 : 7,5 daysdaysAerial Aerial b/wb/w : 6,5 : 6,5 daysdays

IKONOS colorIKONOS color : 3 : 3 daysdays

PRICE:PRICE:

Aerial photos (b/w)= 6,53 €/km2 Aerial photos (color)= 7,84 €/km2IKONOS images = 25,80 €/km2 Quick Bird = 25,80 €/km2

CONCLUSIONCONCLUSION

ArArchiveschives Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick Quick BirdBird

PRICE 6,53 7,84 25,8 25,8Points 5 5 3 3

ArArchiveschives Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick Quick BirdBird

Num. Of Frames 12 12 2 2

Time for aerial triangulations for

defined area: 50 000m2 (days)

2,5 2,5 1 1

Time for orthophotos ortofoto-a (night) 1 1 1 1

Time for color balance and mosaic 3 4 1 1

Summary: 6,5 7,5 3 3

Points: 4 3 5 5

ArArchiveschives Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick Quick BirdBird

Num. Of Frames 12 12 2 2

Days for order: 10-15 10-15 10-15 10-15

Points: 4 4 4 4

New images Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick Quick BirdBird

Num. Of Frames 12 12 2 2

Days for order: 1month 1 month1-3 mont

hs

1-3 month s

Points: 4 4 3 3

InterpretabilityInterpretability Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick BirdQuick Bird

SpectralSpectral 33 44 55 55

GeometricalGeometrical 55 55 33 55

Points:Points: 88 99 88 1010

ArArchiveschives Aerial b/wAerial b/w Aerial colorAerial color IkonosIkonos Quick Quick BirdBird

PRICE 5 5 3 3

TIME for procesing

4 3 5 5

Time for order

4 4 4 4

Interpretability

8 9 8 10

Points: 21 21 20 22