3 research outputs found
Use of multispectral data to identify farm intensification levels by applying emergent computing techniques
Concern about feeding an ever increasing population has long been one of humankind’s
most pressing problems. This has been addressed throughout history by introducing into
farming systems changes allowing them to produce more per unit of land area. However,
these changes have also been linked to negative effects on the socio economic and environmental
sphere, that have created the need for an integral understanding of this phenomenon.
This thesis describes the application of learning machine methods to induct a relationship
between the spectral response of farms’ land cover and their intensification levels from a
sample of farming of Urdaneta municipality, Aragua state of Venezuela. Data collection
like this is a necessary first steep to implement cost-effective methods that can help policymakers
to conduct succesful planing tasks, especially in countries such as Venezuela where,
in spite of there being areas capable of agricultural production, nearly 50% of the internal
food requirements of recent years have been satisfied by importations. In this work, farm
intensification levels are investigated through a sample of farms of Urdaneta Municipality,
Aragua state of Venezuela. This area is characterised by a wide diversity of farming systems
ranging from crop to crop-livestock systems and an increasing population density in
regions capable of livestock and arable farming, making it a representative case of the main
tropical rural zones. The methodology applied can be divided into two main phases. First
an unsupervised classification was performed by applying principal component analysis
and agglomerative cluster methods to a set of land use and land management indicators,
with the aim to segregate farms into homogeneous groups from the intensification point of
view. This procedure resulted in three clusters which were named extensive, semi-intensive
and intensive. The land use indicators included the percentage area within each farm devoted
to annual crops, orchard and pasture, while the land management indicators were
percentage of cultivated land under irrigation, stocking rate, machinery and equipment index
and permanent and temporary staff ratio, all of them built from data held on the 1996-
1997 venezuelan agricultural census. The previous clusters reached were compared to the
ones obtained by applying the learning machine method known as self-organizing map,
which is also an unsupervised classification technique, as a way to confirm the groups’
existence. In the second stage, the learning machine known as kernel adatron algorithm
was implemented seeking to identify the intensification level of Urdaneta farms from a
landsat image, which consisted of two sequential steps: namely training and validation. In
the training step, a predetermined number of instances randomly selected from the data set
were analysed looking for a pattern to establish a relationship between the label and the
spectral response in an iterative process which was concluded when the machine found a
linear function capable of separating the two classes with a maximum margin. The supervised
classification finishes with the validation in which the kernel adatron classifies the
unseen samples by using a generalisation of the relationships learned while training. Results
suggest that farm intensification levels can be effectively derived from multi-spectral
data by adopting a machine learning approach like the one described
Spatial pattern recognition for crop-livestock systems using multispectral data
Within the field of pattern recognition (PR) a very active area is the clustering
and classification of multispectral data, which basically aims to allocate the right class of
ground category to a reflectance or radiance signal. Generally, the problem complexity is
related to the incorporation of spatial characteristics that are complementary to the nonlinearities
of land surface process heterogeneity, remote sensing effects and multispectral
features. The present research describes the application of learning machine methods
to accomplish the above task by inducting a relationship between the spectral response
of farms’ land cover, and their farming system typology from a representative set of
instances. Such methodologies are not traditionally used in crop-livestock studies. Nevertheless,
this study shows that its application leads to simple and theoretically robust
classification models. The study has covered the following phases: a)geovisualization of
crop-livestock systems; b)feature extraction of both multispectral and attributive data
and; c)supervised farm classification. The first is a complementary methodology to represent
the spatial feature intensity of farming systems in the geographical space. The
second belongs to the unsupervised learning field, which mainly involves the appropriate
description of input data in a lower dimensional space. The last is a method based on statistical
learning theory, which has been successfully applied to supervised classification
problems and to generate models described by implicit functions.
In this research the performance of various kernel methods applied to the representation
and classification of crop-livestock systems described by multispectral response
is studied and compared. The data from those systems include linear and nonlinearly
separable groups that were labelled using multidimensional attributive data. Geovisualization
findings show the existence of two well-defined farm populations within the
whole study area; and three subgroups in relation to the Guarico section. The existence
of these groups was confirmed by both hierarchical and kernel clustering methods,
and crop-livestock systems instances were segmented and labeled into farm typologies
based on: a)milk and meat production; b)reproductive management; c)stocking rate;
and d)crop-forage-forest land use. The minimum set of labeled examples to properly
train the kernel machine was 20 instances. Models inducted by training data sets using
kernel machines were in general terms better than those from hierarchical clustering
methodologies. However, the size of the training data set represents one of the main
difficulties to be overcome in permitting the more general application of this technique
in farming system studies. These results attain important implications for large scale
monitoring of crop-livestock system; particularly to the establishment of balanced policy
decision, intervention plans formulation, and a proper description of target typologies to
enable investment efforts to be more focused at local issues