Assessing the accuracy of Orthophotos in identification of land parcel boundary for Cadastral mapping in Kashari sub-county.

Abstract

Land registration in Uganda has moved on quite slowly, it’s estimated that 20% of the country has been covered with the biggest percentage of land being unregistered. This research investigates a system that would be used to facilitate quick production of reliable, accurate and up-to-date cadastral maps used for land mapping through the use of orthophotos. This study aimed at assessing the accuracy of orthophotos in mapping of land parcel boundaries. An orthophoto was obtained from the department of surveys, land parcels were successfully identified and mapped using the orthophoto. The results obtained were then compared with the ground data obtained and cadastral data which acted as the validation data (reference data). Further tests were carried out to evaluate the spatial accuracy of the survey, root mean square area (RMSE) was used to compute the error between the parcels obtained from orthophotos, ground truthing and cadastral data. From the comparison made, it was found out that the results obtained from the orthophotos diverged with a metre accuracy from the ground truth data hence it was concluded that orthophotos should only be used in rural areas with clear general boundaries and where the smaller error in metre is insignificant due to big chunks of land and accuracy is not sensitive.. Therefore it was recommend that mapping using orthophotos should be mostly used in rural areas with general boundaries like hedges, fence and this would reduce the slow progress of land registration. Also up-to-date orthophotos with high resolution should be used and finally extension of controls in the study area should be done in order to geo-reference the orthophotos hence reducing the errors.