412 research outputs found
JSC earth resources data analysis capabilities available to EOD revision B
A list and summary description of all Johnson Space Center electronic laboratory and photographic laboratory capabilities available to earth resources division personnel for processing earth resources data are provided. The electronic capabilities pertain to those facilities and systems that use electronic and/or photographic products as output. The photographic capabilities pertain to equipment that uses photographic images as input and electronic and/or table summarizes processing steps. A general hardware description is presented for each of the data processing systems, and the titles of computer programs are used to identify the capabilities and data flow
Wetland mapping from digitized aerial photography
Computer assisted interpretation of small scale aerial imagery was found to be a cost effective and accurate method of mapping complex vegetation patterns if high resolution information is desired. This type of technique is suited for problems such as monitoring changes in species composition due to environmental factors and is a feasible method of monitoring and mapping large areas of wetlands. The technique has the added advantage of being in a computer compatible form which can be transformed into any georeference system of interest
Deep multiband surface photometry on star forming galaxies: II. A volume limited sample of 21 emission lines galaxies
We present deep surface photometry of a volume--limited sample of 21 UM
emission line galaxies in broadband optical UBVRI and near infra-red (NIR) HKs
filters. The sample comprises 19 blue compact galaxies (BCGs) and two spirals.
For some targets the exposure times are the deepest to date. For the BCG UM462
we observe a previously undetected second disk component beyond a surface
brightness level of mu_B=26 mag arcsec^{-2}. This is a true low surface
brightness component with central surface brightness mu_0=24.1 mag arcsec^{-2}
and scale length h_r=1.5 kpc. All BCGs are dwarfs, with M_B>=-18, and very
compact, with an average scale length of h_r~1 kpc. We separate the burst and
host populations for each galaxy and compare them to stellar evolutionary
models with and without nebular emission contribution. We also measure the
A_{180} asymmetry in all filters and detect a shift from optical to NIR in the
average asymmetry of the sample. This shift seems to be correlated with the
morphological class of the BCGs. Using the color-asymmetry relation, we
identify five BCGs in the sample as mergers, which is confirmed by their
morphological class. Though clearly separated from normal galaxies in the
concentration-asymmetry parameter space, we find that it is not possible to
distinguish luminous starbursting BCGs from the merely star forming low
luminosity BCGs.Comment: 48 pages, 39 figures, submitte
Feasibility Of Caribou Winter Habitat Analysis Using Satellite Data
Thesis (Ph.D.) University of Alaska Fairbanks, 197
Water color and circulation southern Chesapeake Bay, part 1
Satellite imagery from two EREP passes over the Rappahannock Estuary of the Chesapeake region is analyzed to chart colored water types, to delineate color boundaries and define circulatory patterns. Surface observations from boats and helicopters concurrent with Skylab overpass define the distributions of suspended sediment, transparency, temperature, salinity, phytoplankton, color of suspended material and optical ratio. Important features recorded by the imagery are a large-scale turbidity maximum and massive red tide blooms. Water movement is revealed by small-scale mixing patterns and tidal plumes of apparent sediment-laden water. The color patterns broadly reflect the bottom topography and the seaward gradient of suspended material between the river and the bay. Analyses of red, green and natural color photos by microdensitometry demonstrate the utility of charting water color types of potential use for managing estuarine water quality. The Skylab imagery is superior to aerial photography and surface observations for charting water color
A comparison of unsupervised classification procedures on LANDSAT MSS data for an area of complex surface conditions in Basilicata, Southern Italy
Two unsupervised classification procedures were applied to ratioed and unratioed LANDSAT multispectral scanner data of an area of spatially complex vegetation and terrain. An objective accuracy assessment was undertaken on each classification and comparison was made of the classification accuracies. The two unsupervised procedures use the same clustering algorithm. By on procedure the entire area is clustered and by the other a representative sample of the area is clustered and the resulting statistics are extrapolated to the remaining area using a maximum likelihood classifier. Explanation is given of the major steps in the classification procedures including image preprocessing; classification; interpretation of cluster classes; and accuracy assessment. Of the four classifications undertaken, the monocluster block approach on the unratioed data gave the highest accuracy of 80% for five coarse cover classes. This accuracy was increased to 84% by applying a 3 x 3 contextual filter to the classified image. A detailed description and partial explanation is provided for the major misclassification. The classification of the unratioed data produced higher percentage accuracies than for the ratioed data and the monocluster block approach gave higher accuracies than clustering the entire area. The moncluster block approach was additionally the most economical in terms of computing time
Application of ERTS imagery to the study of caribou movements and winter habitat
There are no author-identified significant results in this report
Simultaneous multi-band detection of Low Surface Brightness galaxies with Markovian modelling
We present an algorithm for the detection of Low Surface Brightness (LSB)
galaxies in images, called MARSIAA (MARkovian Software for Image Analysis in
Astronomy), which is based on multi-scale Markovian modeling. MARSIAA can be
applied simultaneously to different bands. It segments an image into a
user-defined number of classes, according to their surface brightness and
surroundings - typically, one or two classes contain the LSB structures. We
have developed an algorithm, called DetectLSB, which allows the efficient
identification of LSB galaxies from among the candidate sources selected by
MARSIAA. To assess the robustness of our method, the method was applied to a
set of 18 B and I band images (covering 1.3 square degrees in total) of the
Virgo cluster. To further assess the completeness of the results of our method,
both MARSIAA, SExtractor, and DetectLSB were applied to search for (i) mock
Virgo LSB galaxies inserted into a set of deep Next Generation Virgo Survey
(NGVS) gri-band subimages and (ii) Virgo LSB galaxies identified by eye in a
full set of NGVS square degree gri images. MARSIAA/DetectLSB recovered ~20%
more mock LSB galaxies and ~40% more LSB galaxies identified by eye than
SExtractor/DetectLSB. With a 90% fraction of false positives from an entirely
unsupervised pipeline, a completeness of 90% is reached for sources with r_e >
3" at a mean surface brightness level of mu_g=27.7 mag/arcsec^2 and a central
surface brightness of mu^0 g=26.7 mag/arcsec^2. About 10% of the false
positives are artifacts, the rest being background galaxies. We have found our
method to be complementary to the application of matched filters and an
optimized use of SExtractor, and to have the following advantages: it is
scale-free, can be applied simultaneously to several bands, and is well adapted
for crowded regions on the sky.Comment: 39 pages, 18 figures, accepted for publication in A
Skylab EREP Investigations Summary
The problems in the areas of agriculture, range and forestry; land use and cartography; geology and hydrology; oceans atmosphere, and data analysis techniques were investigated and summarized using Earth Resources Experiment Package (EREP) data
Southern Chesapeake Bay Water Color and Circulation Analysis
Satellite imagery from two EREP passes over the Rappahannock Estuary of the Chesapeake region are analyzed to chart colored water types, to delineate color boundaries and define circulatory patterns
- …