MA N M DEVELOPIN o
H
Reform needed of
1 50 000 it are needed:
1:5 OOOor 1:10 s essential, so far there exists is carried out from
- the monumentat ion
- the
- even the and finished in the fierd. Aerial is used for orientation some totar up the cadastral map methods are

the ification method.
As it is wen known, due to the central ive ion Jaws, terrainheightdifferences cause errors in the areas with 0 to 10m ion in x and if an not stereorestituted. Recent aeriar ....
1401"\1"''''1'' is rectified the scale 1: 15
000 and rura f are advised to be suited for rectifications at 1:5
000 sca is acceptable. Areas indicat of approximately 1 mm in maximum of more than 11 m shourd be surveyed by ificat ion a combined method.
I
Thailand. followed stereorest Hut ion ion of areas forseen for landreform in
>60 m (
31- 40 m
21-30 m (6.6%)
11- 20 m (1
0-10 m
F 1 1: f terrainhe ion for landreformareas in Thailand.
1

2. Photoident i fi cat ion
In this chapter the cadastral mapping mE~trIO('oloav has been very SW:CEHisn in delair. This
For a systematic planning of the landreform activities it is very the part icular areas early in advance. to know
Whi Ie high resolution remote sensing arrows a general ion of areas suited for landreform, up to date conventional aerial photography is very helpful for detailed parcel measurement.
Always it should be start ing cadastra I to possess recent aerial
1 :4
1 15 000) when
After the aquisition of aerial with about 2 to 4 bases the control net is distance at blockframe for hod zontal control and about
2 bases distance for vertical control. In addition GPS measurements are foreseen~
This net will be marked in nature. The determined
For the aerial ion near the monument, in relation to which
G are terrestrial determined. It is ant future aerial ions wi be measured means of an being based on a bundle block program ical Plotter and robust est like the BLU H programm Favoured is a PC / AT version of this kind of programs.
The enlargements are be done very at an quickly and for the moment lation. If sufficient lead time is available, instead of the can be introduced for flat scale of 1:4 000 or 1:5 000. This can of the progress in
::u:ul"n'tl"'l rectifications which are already exact on the final
Observing legal matters, the monumentation of corners in the fierd can start, or rectifications. In F 2.1 the use of an for the corners in the field is shown.
Fig. 2.1: Photoidentification of r., ... ."." ... ., in an enlargement

Only clearly identifiable parcel corner points may be pricked in the enlargement.
Not direct visible points wi rr be terretrial measured with respect to visible points in the neighbourhood, to be pricked. This situation win appear on a special sketch. For photoidentification purposes in addition the stereoimagepair is observed, using a stereoscope.
In order to fulfil the requirement of controi (doublecheck) in minimum the length of the parcel borders wi fI be measured in the field.
The enlargements can be used as preliminary map rerated products, but not as a real map substitute due to changes in the scale, while rectifications for frat terrain can completefy replace a map. To speed up stereo measurement, predigitizing of parcel corners and numbers in the enrargements or final digitizing of rectifications is highly recommended.
For enlargements this is followed by stereomeasurement of parcel corner coordinates in U TM and exact area calculation, using an Analytical Plotter. These measurements can already take into consideration the production of topographic and thematic maps.
Derived coordinates, parcel sizes and point numbers as derived from terrestrial as well as photogrammetric evaluation win be stored on tape or disk to be usable for a GIS--system like the ARC-Info.
Finally, among others, the cadastral maps will be automaticafry plotted.
3. Conclusion
The photoidentification method is already well established in Thailand.
Consequently being based on recent enlarged and/or rectified aerial photography it wi II be a cadastral mapping methodology of the future. Comparisons of traditional cadastral maps with cadastral maps as derived from photoidentification and stereorestitution as well as derived from rectification show no significant differences (± 0.2 mm rms at map scale). Total stations, Analytical Plotters and digitizers (for rectification) are foreseen for a GIS data acquisition, which also takes over the final numeric and graphic output.
I V .... 263