AVAILABILITY OF UP-TO-DATE SATELLITE IMAGERY MAPS AT SUITABLE SCALES

SURCON QUESTION: THE AVAILABILITY OF UP-TO-DATE SATELLITE IMAGERY MAPS AT SUITABLE SCALES OF 1:1000 AND LARGER COUPLED WITH THE APPLICATION OF INFORMATION TECHNOLOGY TO PRODUCE GEOSPATIAL DATA BASE WILL RENDER THE SERVICES OF CADASTRAL PRACTICING SURVEYORS MINIMALLY NECESSARY

Surveying is the science of obtaining relative position of features on the earth surface. Surveying concerns itself with capturing spatial data about portions of the earth and representing the information of a map. The science and art of surveying have been applied to a number of disciplines that have become branches of the profession. They include engineering surveying, hydrographic surveying, mining surveying, aerial photogrammetry, satellite remote sensing, and cadastral surveying.

Cadastral surveying describes the boundary of a plot or group of plots by measuring the distances and directions of the boundary lines and depicting them on a plan. Cadastral survey limits itself to perimeter survey, describing only the boundary lines of a plot of land. This limitation could be traced to the purpose of perimeter survey, which is to produce title deed plan (TDP), a registrable instrument for the acquisition of ownership right to a piece of land.

As mentioned above, cadastral surveying represents plots of land on a plan at a large scale so that the description can be clearly seen on paper. However, advances in space technology, geographic information system (GIS) and land information system (LIS) have made the process of map making easier and more efficient. Nowadays, there are satellites orbiting the earth, which produce satellite images at resolution as high as 3metres. This means that any object as little as 3metres long can be captured by the satellites. Through the process of digital mapping, these images can be used to produce digital maps of scale 1:1000 or larger. Boundaries of individual land ownership holdings can be clearly depicted in such maps.

For example, an orthophoto or mosaic of scale 1:1000 or larger will not only show features at the boundaries of parcels, but also give a synoptic view of the area. In a GIS environment, plots can be overlaid on the orthophoto which serves as a base map. The distances and directions of the sides can therefore be determined and coordinates of their corners calculated. Thus, layout of entire residential and industrial zones can be designed in a functional land information system with minimal visit to site.

This technological advancement in surveying and mapping implies certain issues that do not favor cadastral surveying. Firstly, perimeter survey, as we used to know it, for the purpose of producing title deed plan will no longer be necessary, and the cadastral surveyor will no longer be needed to do so. The plots have already been subdivided in the computer system. However, the surveyor will be required to set out the plots on the ground as depicted on the digital map.

Secondly, the cadastral surveyor will also lose his traditional work of layout survey. He will no longer be needed to survey a parcel and subdivide it to plots since the GIS/LIS does so faster and with better accuracy.

However, GIS/LIS has not covered many parts of the country. Therefore, presently cadastral practicing surveyors are having a field day. A time is coming (and it may be sooner than expected) when technology will render the services of cadastral practicing surveyors minimally necessary.

In conclusion, it is necessary to give a word admonition to cadastral surveyors. We should remember that surveying is far bigger than cadastral surveying. In fact, cadastral survey is the least project any surveyor can undertake. It is time for surveyors to put on their thinking cap. It is time to stop scratching at the shore of surveying and launch into the deep sea of geo-informatics where adventure awaits. Modern surveyors should be thinking of new applications of satellite imageries for resource management, geospatial data management, and provision of geo-data to meet human needs and solve problems in navigation, transportation, communication, business management and security. It is time to think of new ways of doing good old surveying to meet the challenges of the time. Surveyors who refuse to think along these lines will soon become minimally necessary.

DISCLAIMER: This material is only an attempt to answer an examination question, though written from a background of solid knowledge and practical experience in Surveying and Geoinformatics. It has not gone through peer review. Therefore, all views and opinions expressed therein remain the responsibility of the author and do not necessarily represent that of any institution.  Feedback on corrections and constructive criticisms are welcome. Thank you.