ASSESSMENT OF LOW COST SMALL FORMAT AERIAL PHOTOGRAMMETRY FOR CADASTRAL MAPPING (CASE STUDY IN KLATEN REGENCY, CENTRAL JAVA, INDONESIA) by Harintaka, et.al Gadjah Mada University - Indonesia 7th FIG Regional Conference Hanoi, Vietnam, 1919-22 October 2009
Introduction Availability of cadastral infrastructure plays important role in land management (to anticipate conflict due to parcel ownership and parcel usage in future) future) Small Format Aerial Photogrammetry (SFAPm) which has advantage in low cost equipment and its operational, efficient, and rapid photo acquisition, is suitable for limited area coverage, about 1.000 ha, SFAPm is efficient since it utilizes amateur digital camera or non metric digital camera equipped on ultra light aeroplane
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Introduction This presentation elaborates utilization of low cost SFAPm for cadastral mapping in Klaten Regency, Central Java, Indonesia. Indonesia. Klaten regency is subsub-urban area, flat and rolling region, region, with rapid growing economic and population The study was carried out in 7 stages, stages, i.e. developing Ground Control Points (GCP), aerial photography survey, interior orientation for each photo, aerial triangulation for entire block photos, performed orthophoto and mosicking, interpretation and delineation of land parcel, and finally evaluation
Methodology
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Equipment
ultra-light aeroplane fixed wing
a
b
c
Equipping a camera and gyro stabilizer on ultra-light aeroplane
TS to measure position of premark point
Result and Discussion
A block of SFAPm
Flight plan and flight path
Example of photo’s metadata
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In order to compute camera’s interior parameter and its stability, we conducted 2 methods of camera calibration: in-field and in-flight/in situ. Elements of Camera’s interior parameters (IOP) which computed: position of camera center, focus, and distortion. If the IOP which modelled/computed using 2 methods have the same quanties, camera is stable. Otherwise, the camera is not stable.
InIn-field Calibration
InIn-flight/inflight/in-situ Calibration
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Aerial Triangulation was performed in 2 scenerio: using weight for each observation and without weight The weight quantities belongs to point measurement on photo coordinate system . Based on our computation, AT using weight has superior accuracy (see graphic).
Aerial Triangulation: Using Weight and without Weight Simpangan Baku Maks Orientasi Kamera Hasil TU
5.0000
S i m p B a k u M a k s (m e n i t)
S i m p B ak u M a ks (m )
Simpangan Baku Maks Posisi Kamera Hasil TU
4.0000 3.0000 2.0000 1.0000 0.0000 X (m)
Y (m)
20.0000 15.0000 10.0000 5.0000 0.0000 Roll (menit)
Z (m)
Tanpa Bobot
Pitch (menit)
Yaw (menit)
Orientasi (Roll, Pitch, Yaw)
Posisi Kamera
Tanpa Bobot
Dengan Bobot
Dengan Bobot
Max Standar Dev for Position (X,Y,Z) Max Standar Dev for Orientation Rerata Residu TKT Hasil TU
Rerata RMS TKT Hasil TU
0.1000 0.0000 -0.1000
Rerata residu X
Rerata residu Y
-0.2000 -0.3000 -0.4000
Rerata residu Z
N il ai R M S (c m )
N i la i R e s id u (c m )
0.2000
14.0000 12.0000 10.0000 8.0000 6.0000 4.0000 2.0000 0.0000 RMS X
-0.5000 Posisi X, Y, Z Tanpa Bobot
Dengan Bobot
RMS Y
RMS Z
Posisi X, Y, Z Tanpa Bobot
Dengan Bobot
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Akurasi Tie Point Hasil TU
Akurasi Titik Cek Hasil TU 70.0000
100.0000 50.0000 0.0000 Mean residu Mean residu Mean residu -50.0000 X Y Z
RMS X
RMS Y
RMS Z
N il a i S i m p B a k u (m m )
N i l a i S i m p B a k u (c m )
150.0000
60.0000 50.0000 40.0000 30.0000 20.0000 10.0000 0.0000 Mean residu X
-100.0000 Tanpa Bobot
Dengan Bobot
ICP Accuracy
Mean residu Y Tanpa Bobot
Mean residu Z
Dengan Bobot
Tie Point Accuracy
EOP which obtained by AT in a block of photos could be used to compute 3D ground coordinate of entire point in overlap area Æ DSM Æ DTM Based on computed EOP and extracted DTM, orthophoto could be generated for every photo Orthophoto has orthogonal projection, equal scale in entire photo, and vertical, so reliable measurement can be done directly on orthophoto. Orthophoto also has been georerefenced, so it was very useful for mosaicing
Visual interpretation and delineation to extract parcel information can be conducted on orthophotos. By utilizing CAD software, dimension and area of each parcel cand be computed.
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Samples of digitized parcels (left) and its overlay on orthophoto (right)
To verify dimension and area of extracted parcels, terrestrial measurement was conducted using Total Station Measured parcel’s area by on screen digitizing and by terrestrial is almost similar. Small discrepancies are obtained on paddy field or open space. On the contrary, large discrepancies are obtained on urban area and dense vegetated area.
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Comparation between Parcel area measured on photo and directly on field 1400 1200 Area (m2)
1000 800 600 400 200 0 1
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10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 Pe rcel Photo (m2)Number Terrestrial (m2)
Conclusion 1. Developing premark and coordinate adjustment for GCP and photogrammetric processing consumed a lot of time 2. Measured parcel’ parcel’s area by on screen digitizing (orthophotos) and by terrestrial is almost similar on clear area 3. In this case, accuracy of parcel measurement on photo is depend on border interpretation and identification and also, orthophoto quality.
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Thank You
Practically, land measurement can be carried out in 2 ways, sporadic or systematic. Systematic land measurement is measurement of massive and clustered parcels on a village or more for land registration. Sporadic land measurement is measurement of one or some parcels which the position are separately in a village
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In Indonesia, every parcel measurement must be recorded on standard BPN’s measurement form (GU- Gambar Ukur, see Figure ). On GU document, all of measurement quantities, such as distance, angle, azimuth, sketch of both parcel and its surrounding, are written. Notes on GU document must be able to reconstruct parcel’s location and its border. This condition is very useful, for instance, if the border’s monuments can not be found in the field. A GU document can be used to record data of some parcels
An example of Indonesian GU or measurement form (Yuwono, et. al, 2008)
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