TassCap: Tasseled Cap transformation

Kauth and Thomas (Kauth, R.J. and Thomas, G.S. "The Tasseled Cap-A graphic description of the spectral-temporal development of agricultural crops as seen by Landsat" (1976) Prec. Symp. On Machine Processing of Remote Sensed Data, Purdue Univ., West Lafayette, Indiana, pp. 41-51.), to improve crop prediction, proposed a transformation that used the four bands of Landsat MSS in linear combinations to produce four indices known as: soil brightness index (SBI), green vegetative index (GVI), yellow stuff vegetation index (YVI) and a fourth with imprecise significance that they called "nonsuch index" (NSI). From a Landsat image, they selected a set of pixel clusters identified as soil and vegetation, and they calculated by the Gram-Schmidt ortogonalization method, the eigenvalues corresponding to the coeficients of the indices.

As Principal Component Analysis (PCA), this transformation allaws obtaining new bands from a linear combination of the original. However, in this case, the new bands have a precise physical meaning: the SBI inform on changes in the total reflectivity of the scene, the GVI indicate the contrast between visible and near infrared bands, closely related to vegetation activity; the YVI is related to the amount of water in vegetation and soil, so that it is usually called Wetness index. It has also called Maturity index since its relation to the vegetation cover maturity (age, cover density, etc.); finally, the NSI is sensitive to water vapor absortion, although most ofits component is noise.

Tasseled Cap has been used in a large number of applications. A drawback of this transform is that it was computed from mid-west american crops and it is not optimized for other regions such as the mediterranean. Another remark is that the Tasseled Cap has been applied to other sensors without considering its characteristics and MSS origins.

TassCap Mode Band1 Band2 Band3 Band4 OutputPrefix