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241.
Jochem Verrelst Gertjan W. Geerling Karle V. Sykora Jan G.P.W. Clevers 《International Journal of Applied Earth Observation and Geoinformation》2009
Combined optical and laser altimeter data offer the potential to map and monitor plant communities based on their spectral and structural characteristics. A problem unresolved is, however, that narrowly defined plant communities, i.e. plant communities at a low hierarchical level of classification in the Braun-Blanquet system, often cannot be linked directly to remote sensing data for vegetation mapping. We studied whether and how a floristic dataset can be aggregated into a few major discrete, mappable classes without substantial loss of ecological meaning. Multi-source airborne data (CASI and LiDAR) and floristic field data were collected for a floodplain along the river Waal in the Netherlands. Mapping results based on floristic similarity alone did not achieve highest levels of accuracy. Ordination of floristic data showed that terrain elevation and soil moisture were the main underlying environmental drivers shaping the floodplain vegetation, but grouping of plant communities based on their position in the ordination space is not always obvious. Combined ordination-based grouping with floristic similarity clustering led to syntaxonomically relevant aggregated plant assemblages and yielded highest mapping accuracies. 相似文献
242.
Yong Ge Sanping Li V. Chris Lakhan Arko Lucieer 《International Journal of Applied Earth Observation and Geoinformation》2009
The existence of uncertainty in classified remotely sensed data necessitates the application of enhanced techniques for identifying and visualizing the various degrees of uncertainty. This paper, therefore, applies the multidimensional graphical data analysis technique of parallel coordinate plots (PCP) to visualize the uncertainty in Landsat Thematic Mapper (TM) data classified by the Maximum Likelihood Classifier (MLC) and Fuzzy C-Means (FCM). The Landsat TM data are from the Yellow River Delta, Shandong Province, China. Image classification with MLC and FCM provides the probability vector and fuzzy membership vector of each pixel. Based on these vectors, the Shannon's entropy (S.E.) of each pixel is calculated. PCPs are then produced for each classification output. The PCP axes denote the posterior probability vector and fuzzy membership vector and two additional axes represent S.E. and the associated degree of uncertainty. The PCPs highlight the distribution of probability values of different land cover types for each pixel, and also reflect the status of pixels with different degrees of uncertainty. Brushing functionality is then added to PCP visualization in order to highlight selected pixels of interest. This not only reduces the visualization uncertainty, but also provides invaluable information on the positional and spectral characteristics of targeted pixels. 相似文献
243.
244.
Ben K. H. Soon Steve Scheding Hyung-Kuen Lee Hung-Kyu Lee Hugh Durrant-Whyte 《GPS Solutions》2008,12(4):261-271
This paper presents a simple and effective approach that incorporates single-frequency, L1 time-differenced GPS carrier phase
(TDCP) measurements without the need of ambiguity resolution techniques and the complexity to accommodate the delayed-state
terms. Static trial results are included to illustrate the stochastic characteristics and effectiveness of the TDCP measurements
in controlling position error growth. The formulation of the TDCP observation model is also described in a 17-state tightly-coupled
GPS/INS iterative, extended Kalman filter (IEKF) approach. Preliminary land vehicle trial results are also presented to illustrate
the effectiveness of the TDCP which provides sub-meter positional accuracies when operating for more than 10 min. 相似文献
245.
V. Nagasubramanian P. V. Radhadevi R. Ramachandran R. Krishnan 《Journal of the Indian Society of Remote Sensing》2008,36(1):27-35
Rational Function Model (RFM) is the alternate sensor Model to the rigorous sensor model that allows end user to perform sensor-independent
photogrammetric processing. Nowadays, commercial off-the-shelf (COTS) digital photogrammetric work stations have incorporated
RFM as a method for image restitution. It is technically applicable to all types of airborne and space borne sensors. In this
paper, we describe the derivations of the algorithmic procedure for third order inverse and forward RFM method for 3-D reconstruction.
Model accuracy is evaluated for aerial image, TK-350 Russian image and IRS-1C PAN image. The results ensure that properly
constructed RFM are accurate enough to be used in place of the original rigorous models. The test results are reported and
summarised. 相似文献
246.
K. N. Prudhvi Raju Sarvajeet Kumar Kshitij Mohan Manish Kumar Pandey 《Journal of the Indian Society of Remote Sensing》2008,36(3):283-288
With growing urban expanses, one of the pre-requisites for effective governance is Urban Information Systems (UIS) with content
down to individual properties (and individuals). The basic input i.e., a map, in UIS should show individual property boundaries
showing the plan outline of all structures existing within, at a scale of 1:1000 and larger with sub-metre to centimeters
planimetric and geometric accuracy. With very high resolution remote sensing data of the order of 1m available in hand, it
is possible to prepare maps with high resolution spatial content. The present exercise demonstrates a method of preparing
a geometrically and planimetrically accurate urban cadastral map on very large scale for a small area of about 5 sq km. IKONOS
merged data with 1m resolution is used for the purpose. Mapping was done in conjunction with on-site measurements and sketches.
Guides are used to maintain shape symmetry and accuracy of buildings and other features. Working out cost of mapping per unit
area is another objective in the present exercise. For want of fully or semi-automatic methods of information extraction from
very high resolution remote sensing data, it is imperative that mapping should be carried out in conjunction with some on-site
measurements wherever necessary. 相似文献
247.
248.
Airborne LiDAR has found application in an increasing number of mapping and Geo-data acquisition tasks. Apart from terrain
information generation, applications such as automatic detection and modeling of objects like buildings or vegetation for
the generation of 3-D city models have been explored. Besides the height itself, height texture defined by local variations
of the height is a significant parameter for object recognition. The paper explores the potential of the analysis of height
texture as a cue for the automatic detection of objects in LiDAR datasets. A number of texture measures were computed. Based
on their definition and computation these measures were used as bands in a classification algorithm, and objects like buildings,
single trees, and roads could be recognized. 相似文献
249.
This study proposes a bootstrap-based space–time surveillance model. Designed to find emerging hotspots in near-real time, the bootstrap based model is characterized by its use of past occurrence information and bootstrap permutations. Many existing space–time surveillance methods, using population at risk data to generate expected values, have resulting hotspots bounded by administrative area units and are of limited use for near-real time applications because of the population data needed. However, this study generates expected values for local hotspots from past occurrences rather than population at risk. Also, bootstrap permutations of previous occurrences are used for significant tests. Consequently, the bootstrap-based model, without the requirement of population at risk data, (1) is free from administrative area restriction, (2) enables more frequent surveillance for continuously updated registry database, and (3) is readily applicable to criminology and epidemiology surveillance. The bootstrap-based model performs better for space–time surveillance than the space–time scan statistic. This is shown by means of simulations and an application to residential crime occurrences in Columbus, OH, year 2000. 相似文献
250.