M. Lorraine Tighe, PhD
Dr. Tighe has a Ph.D. in Earth Sciences, a graduate degree in Remote Sensing and GIS, and a B.Sc. in Physics and Geology. Dr. Tighe has delivered lectures ranging from a half day workshop to a 4 week training program to over 2000 participants in USA, Canada, Jamaica, Brazil, Ecuador, Honduras, … More »
Oil Palm Plant Phenological Stages Identified Using High Resolution Radar Imagery
September 10th, 2013 by M. Lorraine Tighe, PhD
Oil Palm plantations cover more than 700,000 hectares in East Sabah, Malaysia. Sabah also has the highest yield of oil palm fresh fruit bunch per hectare, in Asia. Moreover, oil palm crops are an important agriculture sector for the Malaysian economy in terms of export earnings, since it contributes to >30% of the total income from exports. Accurate and reliable three dimensional and near-real time geospatial information is needed for sustainable oil palm plantation management, especially on plant quality, health, and crop yield calculations.
High-resolution X-band HH (horizontal transmitted, horizontal received) radar imagery, like that from NEXTMap® ORI, afford the identification of plantations and orchards, making it possible to even count the number of, for example, oil palm plants within an orchard. This is critical information used in the calculation of crop yield. The identification of oil palm plants and plantations are made possible with the aid of a radar interpretation key (like the one presented here). The key is based on traditional photogrammetric methods where the use of imagery tone, texture, size, pattern, etc. provide keys or clues that help to identify features like an orchard or individual plants in a radar image. Let us examine that application a little closer.
Oil palm plants, with their characteristic structures, affect the radar signal returned to a SAR sensor differently during different phenological stages (e.g. young, mature, and harvested crop). A young oil palm crop will exhibit dihedral scattering from the base of the trunk of the plant to yield a bright dot on a radar image (far left image chip, called young); whereas, a mature oil palm crop will exhibit diffuse and volumetric scattering to yield an overall bright image tone with rich radar texture as seen in the middle image (mature). Thus, one would use the young oil palm phenological stage to count the number of plants in an orchard. When an oil palm crop has been harvested and the oil palm pods have been removed, the overall image tone will be dark, with lighter dots representing low returns from the trunks of the plants (far right image, harvested).
Category: Geospatial Application