In the rapidly advancing technological age, virtual
environments are becoming increasingly prevalent. Video games and virtual reality have put the
users in the middle of the action to immerse them in a completely simulated
setting. Is this just a phase? Or, will virtual reality be a major component
of spatial learning and understanding for future generations? Before, Southwestern University’s virtual
tour is comprised of photos and brief snippets of information. By using and working with Google, the user
can navigate the campus similarly to Google Streetview. Now, it is a virtual environment, made up of
360-degree panorama points where the user can look up, down, and all around the
SU campus from their computer or smartphone.
This innovative use of the Google platform to work with a virtual tour
of campus has not been done in this capacity before and would test the limits
of this tool and of virtual environments in general.
Friday, December 13, 2013
The Effect of Damming on the Blanda River Flow Regime
Iceland is one of the only countries in the world that can
claim to have a completely clean energy portfolio. The demand for hydropower is still
increasing, and Iceland has dammed many of its rivers to meet this need at the
expense of their riparian ecosystems.
The regulation of flow regimes and creation of reservoirs has had a
significant impact on the ecosystems in and around the rivers of Iceland. The Blanda River has been utilized for
hydropower since the early 1990’s, and will be used to model the effect of the
dam on the downstream flow regime using Digital Elevation Modeling and Flow
Accumulation. By using these models
along with river flow data, we will be able to analyze the effects felt as a
result of the dam.
Tuesday, December 3, 2013
Proper Systems of Land Use: Farming
Source:
Global Consequences of Land Use
Jonathan A. Foley et al. Science 309, 570 (2005);
DOI: 10.1126/science.1111772
When thinking about Land Use, the general population tends to think more on a scale of deforestation, habitat destruction, logging, and farming. Things that are relatively brought up or seen in your daily activities. In this study about Land Use, it is concluded that "subsistence agriculture, clearing tropical forests, intensifying farm production and expanding urban centers" is changing the makeup of the worlds landscapes and at the expense of the environment.
An example of this is found through comparing different types of land and the trade offs of human activity on these land types.
In these diagrams we find that while maintaining a Natural Ecosystem is beneficial to the ecosystem, we clash with the ecosystem as we do not benefit financially and do not benefit from the land we considered to be "not used". In an Intensive Cropland, we essentially destroy the natural landscape and soil makeup. There is no natural regulation other than possibly restarting a new crop every year. If you look at the Cropland with Restored Ecosystem Services, it is depicted that there is a mutual abundance of natural and human based eco-services.
While food and crop production has been beneficial in supporting the human population, particularly in the U.S, there is a correlation with intensified farming and environmental damage. eg: Increased use of fertilizer correlates to poor water quality, soil erosion and overgrazing leads to complete loss of arable land.
The continuance of uninformed farmers, ranchers, and land owners not practicing sustainability with the land the practice on will ultimately result in a more widespread disaster of climate change.
Global Consequences of Land Use
Jonathan A. Foley et al. Science 309, 570 (2005);
DOI: 10.1126/science.1111772
When thinking about Land Use, the general population tends to think more on a scale of deforestation, habitat destruction, logging, and farming. Things that are relatively brought up or seen in your daily activities. In this study about Land Use, it is concluded that "subsistence agriculture, clearing tropical forests, intensifying farm production and expanding urban centers" is changing the makeup of the worlds landscapes and at the expense of the environment.
An example of this is found through comparing different types of land and the trade offs of human activity on these land types.
In these diagrams we find that while maintaining a Natural Ecosystem is beneficial to the ecosystem, we clash with the ecosystem as we do not benefit financially and do not benefit from the land we considered to be "not used". In an Intensive Cropland, we essentially destroy the natural landscape and soil makeup. There is no natural regulation other than possibly restarting a new crop every year. If you look at the Cropland with Restored Ecosystem Services, it is depicted that there is a mutual abundance of natural and human based eco-services.
While food and crop production has been beneficial in supporting the human population, particularly in the U.S, there is a correlation with intensified farming and environmental damage. eg: Increased use of fertilizer correlates to poor water quality, soil erosion and overgrazing leads to complete loss of arable land.
The continuance of uninformed farmers, ranchers, and land owners not practicing sustainability with the land the practice on will ultimately result in a more widespread disaster of climate change.
Monday, December 2, 2013
Abstract: Food Miles Behind Nepali Coffee
Nepal’s coffee sector has grown dramatically within the past decade and is predicted to continue expanding in the coming years. The demand for Nepali coffee in both local and international markets is increasing; Nepali coffee is steadily establishing a firmer position in the world coffee market. While some of the coffee farmers that comprise Nepal’s coffee sector operate independently, many have organized themselves into coffee cooperatives to share resources, expand market access, and secure higher premiums for their beans. The effects of these cooperatives often extend beyond coffee farming to other domains of members’ lives. With a predicted increase in coffee production and number of coffee cooperatives, it is worthwhile to evaluate how cooperatives are reshaping the lives and livelihoods of their members. By using GIS mapped out the food miles behind Nepali coffee from the farmers, to the cooperative, to the storefront, mainly using data coordinates. This research provided insight regarding the challenges for coffee farmers and the effort that is behind every cup of Nepali coffee.
Monday, November 11, 2013
Georgetown City Park Locations Compared to Median Household Income Values
Want
to go outside and play? Find a park, Georgetown is full of them. In fact, there
are 30 city parks total. Referring to
the Georgetown Parks website, I plotted the location of 28 out of 30 city
parks. Then, I used Fact Finder on the Census website to map out reported
median incomes in Williamson County. There is a higher density of parks in the
lowest income bracket in Georgetown. The middle brackets have few parks. The
upper middle class has many parks separated by at least a mile. The upper class
subdivision does not have any public parks.
Notice,
each income level is distinctly separated in Georgetown. The highest income
level lies farthest away from the downtown, while the lowest income levels are
nearest the downtown. Parks may be more prevalent in lower income areas because
there is a higher need, whereas upper class subdivisions tend to have larger
private yards. More, the low income sector in Georgetown also overlaps the
historic district. Perhaps, the parks were built first and as development
spreads north, there are fewer parks being built.
Thursday, November 7, 2013
GTography: Breakfast Tacos in Georgetown, Texas
Texas is known for serving delicious breakfast tacos, especially in the Austin/Georgetown area. This map displays all of the restaurants that serve breakfast tacos in Georgetown. I used yellowpages.com to find the addresses, uploaded them onto arcgis.com, and created a map displaying the locations. The map shows an interesting clustering of restaurants right off of highway I-35, and also on the main streets that lead to I-35. The clustering in these areas probably occur because people would rather stop somewhere on route to their workplace, rather than go completely out of their way, when commuting to work.
Abstract: Correlations Between SAT Scores and Potential Influential Factors
High school students must take the SAT and/or ACT before applying to college in the United States. SAT and ACT scores are considered important in determining a student’s acceptance to their desired school. However, some may argue that these standardized tests may be biased, and influenced by factors other than a student's abilities in math, reading, and writing. For example, does the parental status of the student (e.g. divorced, married, single) have any correlation with the scores? In this project, the Texas Education Agency's annual report on college admissions testing for high school seniors in public schools was used to create a visual representation of SAT combination reading and writing scores across the state. In order to create a map with an uninterrupted range of scores, versus simply an accumulation points, the data was interpolated. Statistical analyses compared the scores to important factors such as race and ethnicity, household income, parental status, etc. These analyses revealed significant correlations between SAT scores and the above factors, suggesting that the scores may not be an accurate assessment of student's math, reading, and writing scores.
Wednesday, October 30, 2013
Land use in Belize
In this article the author explores deforestation in Belize
and the impact that road making has on the landscape and development of the
country. Roads are what allow access to remote forests in the country and they
do not always lead to the most efficient use of the land. The author suggests
that is GIS methods were put into use by the people making the road then the
land could be use more efficiently. By studying the land through the use of GIS
it is more likely that road planners would have a better idea of what resources
these roads may lead to so that trees are not needlessly cut down in vain. By planning
out the use of land spatially and in the context of the environment, rather
than just clear cutting a road, there can be a cut down on unneeded loses.
By following the model of von Thiinen and the equations that
can better determine the cost and benefits of land use we can put value to the
land so that a plot of land is used to its best economic and environmental
potential. Methods like this and GIS can be used to better plan out the use of
land not only in Belize but really anywhere there is land to be developed.
Chomitz, Kenneth M., and David A. Gray. "Roads, Land Use, and Deforestation: A Spatial Model Applied to Belize." Oxford University Press, n.d. Web.
Wednesday, October 23, 2013
Abstract: Ecuador's Rose Farms
Behind Colombia, Ecuador is the world's leading exporter of cut roses. In addition, they export numerous other cut flowers. The United States of America is the number one consumer of Ecuadorian roses, and the rose floriculture provides significant economic impact in both Ecuador and the U.S.A. This project's aim is to provide a visual of rose farm concentration in Ecuador and provide market information on the quality of roses as it relates to altitude. A map such as this does not exist, and as such, this map will provide a social service to the rose growers in Ecuador. ExpoFlores, an organization that manages the social and environmental impact and image of the Ecuador's flower farms, provides a list of farms. From this list, I will create my own specific list of rose farms. Luckily, most farms have a website;however, most do not list the address, but the town. Since the exact locations of farms are not always provided, I will use Normalized Digital Vegetation Difference (NDVI) technology through ArcGIS online to locate the farms.
Digital Elevation Models (DEM) will be used to determine the altitude of the farms. Rose growers in Ecuador claim roses grow taller, stronger and straighter with higher altitudes. Once I have the farms location and altitude plotted, I will refer to sights such as FlorEcuador and ExpoFlores to see if the quality of the rose does indeed correspond to the altitude. If the DEM model proves to be too time intensive, I will then plot all flower farms to create a map which models concentration of rose farms compared to other flowers.
Sunday, October 20, 2013
Industrial Evolution in Austin, Texas: From Environmental Hazards to a High-Tech Explosion (Abstract)
Grady Sampley
Abstract:
As the Capital of Texas, Austin has always been a major epicenter and leader for Texas economic and cultural progression. Generally, Texas has been known for their large-scale manufacturing industry wherein the petrochemical sector takes the lead. This highly industrial economy and culture carries along with it a variety of environmentally hazardous byproducts. Austin has also historically absorbed this kind of large-scale manufacturing industry as will be shown in this project via GIS applications using the Toxic Release Inventory (TRI); however, as it has advanced into modern times, Austin has moved towards a more innovative, creative, eco-friendly, and high-tech culture and economy. This budding cultural and economic change has resulted from the influx of young and educated populations who are mainly attracted to Austin’s unique and recently fostered progressive reputation which, in turn, prompted the explosion of its high-technology industrial sector generally due to the abundance of suitable potential employees. To show this explosion of high-tech industry within the Austin area my project uses the “Directory of Austin-Area High-Tech Firms” produced by The Greater Austin Chamber of Commerce in unison with GIS mapping applications. Through the utilization of both TRI and this directory, my project will illustrate the evolution of Austin’s Industrial landscape from a large-scale manufacturing industry – along with its environmentally hazardous byproducts – towards a much more clean, creative, and innovative high-tech industry. With these illustrations, my project analyzes the positive and negative implications of this industrial evolution on Austin’s socio-economic landscape.
Abstract:
As the Capital of Texas, Austin has always been a major epicenter and leader for Texas economic and cultural progression. Generally, Texas has been known for their large-scale manufacturing industry wherein the petrochemical sector takes the lead. This highly industrial economy and culture carries along with it a variety of environmentally hazardous byproducts. Austin has also historically absorbed this kind of large-scale manufacturing industry as will be shown in this project via GIS applications using the Toxic Release Inventory (TRI); however, as it has advanced into modern times, Austin has moved towards a more innovative, creative, eco-friendly, and high-tech culture and economy. This budding cultural and economic change has resulted from the influx of young and educated populations who are mainly attracted to Austin’s unique and recently fostered progressive reputation which, in turn, prompted the explosion of its high-technology industrial sector generally due to the abundance of suitable potential employees. To show this explosion of high-tech industry within the Austin area my project uses the “Directory of Austin-Area High-Tech Firms” produced by The Greater Austin Chamber of Commerce in unison with GIS mapping applications. Through the utilization of both TRI and this directory, my project will illustrate the evolution of Austin’s Industrial landscape from a large-scale manufacturing industry – along with its environmentally hazardous byproducts – towards a much more clean, creative, and innovative high-tech industry. With these illustrations, my project analyzes the positive and negative implications of this industrial evolution on Austin’s socio-economic landscape.
Wednesday, October 16, 2013
Mexican-American Socioeconomic Status and Obesity
Source:
Fisher-Hoch SP, Rentfro
AR, Salinas JJ, Pérez A, Brown HS, Reininger BM, et al.
Socioeconomic status and prevalence of obesity and diabe-
tes in a Mexican American community, Cameron County,
Texas, 2004-2007. Prev Chronic Dis 2010;7(3)
In this article, the risk for obesity and diabetes is examined in a small county on the U.S-Mexico border in Texas. The study is partial to Mexican-Americans, as the county is predominately made up of Mexican-Americans. Randomly selected and studied persons aged 35-64 year olds are looked at along with their socioeconomic status and the correlation to diabetes risk along with obesity. The final sample, after going through multiple cuts to make the sample more accurate, was made up of all hispanics with 68% being female.
Variables such as, BMI, waist circumference, fasting blood glucose and insulin were taken into account. They then took this information and compared it too the annual household income, using GIS "to visualize spatial distribution" by different income quartiles. The findings were phenomenal, as this county was found to have a large uninsured racial minority population. People in the lower income stratum were found to be more likely to have undiagnosed diabetes, as the risk increases with age. Oddly enough, there were no differences between socioeconomic status with prevalence of obesity.
In this article, the risk for obesity and diabetes is examined in a small county on the U.S-Mexico border in Texas. The study is partial to Mexican-Americans, as the county is predominately made up of Mexican-Americans. Randomly selected and studied persons aged 35-64 year olds are looked at along with their socioeconomic status and the correlation to diabetes risk along with obesity. The final sample, after going through multiple cuts to make the sample more accurate, was made up of all hispanics with 68% being female.
Variables such as, BMI, waist circumference, fasting blood glucose and insulin were taken into account. They then took this information and compared it too the annual household income, using GIS "to visualize spatial distribution" by different income quartiles. The findings were phenomenal, as this county was found to have a large uninsured racial minority population. People in the lower income stratum were found to be more likely to have undiagnosed diabetes, as the risk increases with age. Oddly enough, there were no differences between socioeconomic status with prevalence of obesity.
Wednesday, October 2, 2013
Conservation of Viperids in North-West Africa Using Ecological GIS
As you can see in this first image, the use of raster data is crucial in the determination of the landscape of various regions in this section of NW Africa. This map also includes vector data of the points at which the various species of snakes are located. These two types of data are combined to create the map below, which shows the different species of snakes along with the likely overlap of species in the various regions.
The knowledge of the density and variety of viperids in the various biomes of NW Africa is instrumental in their conservation. Knowing the variety and density of viperids in each type of habitat allows conservation biologists to tailor the conservation programs to the individual scenarios that occur.
- Brito et al., 2011
- J.C. Brito, S. Fahd, P. Geniez, F. MartÃnez-FreirÃa, J.M. Pleguezuelos, J.-F. Trape
- Biogeography and conservation of viperids from North-West Africa: an application of ecological niche-based models and GIS. Journal of Arid Environments, 75 (11) (2011), pp. 1029–1037
Links in Diabetes Rate Among Mexican American
Mexican Americans are more likely to have diabetes than any
other ethnic group in the United States. Many believe that this is because the
disease is genetic but may in part be due to the lower economic status of this
ethnic group. Many cannot afford the decent health care that can identify early
warning signs of diabetes and they do not get treatment right away.
Using GIS we can conclude that many of the clusters of
diabetes form near the border to Mexico. The correlation between higher risks
of diabetes and these areas is due largely to the socioeconomic status. Many
Mexican Americans living along border towns are not wealthy and therefore
cannot afford proper medical care. It can be seen that with better medical care
comes less cases of diabetes among Mexican Americans. People who can afford the
better medical care will be healthier and it shows among this particular group
of people. This data can be useful for government agencies wishing to release
funds for better medical care among struggling communities.
Swine Flu 2010
When the Swine Flu (H1N1) outbreak occurred in 2009 many
people feared this outbreak. But by using GIS techniques scientists could be
able to better watch out for an outbreak and know how to react when such a case
happens. In Brownsville Texas GIS data is used to track past information about
outbreaks of diseases from previous years. They can use this data to identify
clusters where the disease may have sprung from or where it began spreading. If
a certain disease is spreading rapidly in one specific area consistently, there
may be some reason for this.
After you get a general feel for where and how severely
specific influenza type diseases like ILI, RIDT, and S-OIV spread in a town
like Brownsville, you can compare this to a new disease like Swine Flu and get
a general idea for where your front line defenses should be. By mapping out
specific danger zones you can actually be better prepared for when a major
disease hits a city. When Swine Flu hit the city of Brownsville the city
officials had a better idea of where care for the disease would be necessary
and that way they were better prepared.
Austin 2002 Species Distribution
Scientists are starting to use geographic information systems (GIS) to track growth and extent of plant life in a specific area. This information can be used to understand and predict the trends in certain species of plants. They can visually see growth, decline, or migrations that might be occurring and use that information to get a general idea of how a species is competing.
In order to get a good understanding of the environment
there are three models of information that need to be taken into account, the
ecological model, a data model, and a statistical model. The ecological data is
information that can be taken from the field and tested to find results. The
data model is the numerical value of the ecological findings and the
statistical model measures the level of error and determines the significance. We
can now see trends and find possible reasons for a change in a species and
natural ecosystem of this specific area. Discrepancies between process model and
statistical model will demonstrate our lack of knowledge and may also indicate
the way forward. Different environmental factors affect specific areas
differently.
Monday, September 30, 2013
GIS employed in California's Supplemental Nutrition Assistance Program (SNAP)
Stone, M. (2011). Enhancing the delivery of supplemental nutrition assistance program education through geographic information systems. Journal of Nutrition Education and Behavior, 43(4, Suppl 2), S148-S151. doi: 10.1016/j.jneb.2011.01.009
Link: http://www.nursingconsult.com/nursing/journals/1499-4046/full-text/PDF/s149940461100042x.pdf?issn=1499-4046&full_text=pdf&pdfName=s149940461100042x.pdf&spid=24335937&article_id=849514
The California Department of Public Health and the USDA has began an initiative known as The Network for a Healthy California (known as Network) to educate individuals who are eligible for the Supplemental Nutrition Assistance Program (SNAP). In order to be eligible, the person's household income should be below 185% of the federal poverty level.
The Network implements GIS technology to geographically identify areas of California that contain large numbers of eligible individuals. GIS is used to identify eligible census tracts, low-resource schools, and community sites (i.e. unemployment housing or food banks).
Network users also use GIS to create layers of varying information, from the California Fitness-gram scores to the number of fast-food restaurants available to students within a half-mile of school. Currently, the Network has 122 layers available for spatial analysis.
The maps that result from these spatial analyses are used to influence policy makers decisions and engage the neighborhoods that are identified.
Link: http://www.nursingconsult.com/nursing/journals/1499-4046/full-text/PDF/s149940461100042x.pdf?issn=1499-4046&full_text=pdf&pdfName=s149940461100042x.pdf&spid=24335937&article_id=849514
The California Department of Public Health and the USDA has began an initiative known as The Network for a Healthy California (known as Network) to educate individuals who are eligible for the Supplemental Nutrition Assistance Program (SNAP). In order to be eligible, the person's household income should be below 185% of the federal poverty level.
The Network implements GIS technology to geographically identify areas of California that contain large numbers of eligible individuals. GIS is used to identify eligible census tracts, low-resource schools, and community sites (i.e. unemployment housing or food banks).
Network users also use GIS to create layers of varying information, from the California Fitness-gram scores to the number of fast-food restaurants available to students within a half-mile of school. Currently, the Network has 122 layers available for spatial analysis.
The maps that result from these spatial analyses are used to influence policy makers decisions and engage the neighborhoods that are identified.
Sunday, September 29, 2013
Obesity and Diabetes Trends in Cameron County, Texas
Fisher-Hoch, Susan et al (2010). Socioeconomic Status and Prevalence of Obesity and Diabetes in a Mexican American Community, Cameron County, Texas 2004-2007, Preventing Chronic Disease: Public Health Research, Practice and Policy. 7 (3), 1-10.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879985/
This study relied on data from the Cameron County Hispanic Cohort (CCHC) to determine the prevalence of obesity and diabetes in Mexican American populations. Specifically, the study examined the affect of socio-economic status on obseity and diabetes rates. The CCHC now numbers 2,000 people aged 35-60 years. Of these, 810 people were randomly selected for the study.
Income was divided into four stratas. Researchers targeted the first strata (the lowest earning) and the third strata (a higher earning group). The lower earning strata had a median income of $17,830 or less; higher earning, $24,067-$31,747. There were more participants representing the lower strata than the higher.
Two nurses and four field workers, all bilingual and bicultural, conducted the study. They had each participant fast for ten hours prior to examinations and rescheduled the exam if they did not fast. During the exam, they measured weight, height, body mass index (BMI), blood pressure, waist circumfrance, insulin levels and blood glucose levels. BMI was used as a measure of obesity.
Results showed that over half of the participants in both income stratas reported a BMI in the obese range. 57% in the lower income strata were obese; 55.5%, in the higher. Less than a half of participants reported insurance, and only five percent reported Medicaid coverage. More women than men were able to participate in the study, because the men tended to work hourly wage jobs.
The study concludes that income is a direct influencing factor contributing to obesity and diabetes. This study is the first of its kind to focus exclusiviely on Mexican Americans in a border city. Results coincide with already published studies which show that the rate of diabetes in Latino communities is twice that of non-Hispanic white communities.
Saturday, September 28, 2013
Impacts of Urbanizaiton on the Environment in China
Source:
Wong, Q. 2001. A
remote sensing–GIS evaluation of urban expansion and its impact on surface
temperature in the Zhujiang Delta, China.
International Journal of Remote
Sensing, 22(10): 1999-2014.
The Zhujiang Delta region of China is
one of the largest areas of economic concentration in Southern China, and as
such has experienced rapid urbanization during the years since the
implementation of China’s economic reform policies. It is also one of the richest agricultural
regions. With the rapid urbanization
process changing the land-use patterns of the region, and keeping in mind the
Urban Heat Island phenomenon, in which urban areas tend ot have higher surface
temperatures than surrounding areas, Wong attempted to use satellite imaging and
GIS analysis technology to study the pattern of urbanization and determine its
effects on the surrounding environment.
Wong identified 7 types of land use using
LANDSAT images of the region for both 1989 and 1997, and then quantified the
changes land use between the two with a matrix.
These images were then overlaid in a GIS system to represent the data on
land use changes in a single image detailing the overall changes. Another layer, containing data on roads in
the region, was added to the GIS system and a buffer was added to that data to
determine the correlation between urbanization and the distance from major
roadways.
After that, radiant surface
temperature data from each year, obtained from LANDSAT TM thermal infrared data,
was added to the GIS system and an algorithm was used to determine the change
between the 8 year period. Combining
these elements in the GIS system allowed for the spatial analysis of the
correlation between urbanization trends and increases in surface temperatures
between 1989 and 1997.
This allowed Wong
to conclude that not only has increased surface temperature correlated to
increased urbanization, but also that greater urbanization has occurred in
rural areas and in closer proximity to roadways. It also presented interesting data regarding two other land uses. Surface temperature increases were also correlated with barren land use as well as non-traditional horticultural lands, though to a lesser extent. Higher
temperatures were also found in certain water bodies, which Wong hypothesized might be a result
of increased sediments and other particles in the water from greater
urbanization and industrial run-off.
This demonstrates other potential uses of GIS analysis in determining impacts
of urbanization and land use change on the environment.
Scale in GIS: An overview
F. Goodchild, Michael (2011). Scale in GIS: An overview. 130 (2011), 5-9.
This review article discusses the relevance of scale, as a
disciplinary problem, within GIS and geomorphology. Three general problems of scale are
discussed, then two methods for conceptualizing phenomena, raster vs. vector
data, problems specific to GIS & modeling, & lastly, methods of
formalizing scale within various disciplines.
The first problem of scale is semantic. Scale is used in 3 senses in science:
1)
Cartographers refer to the representative fraction as the parameter that defines the scaling
of the earth to a sheet of paper
a.
ratio between map/ground
b.
defines level of detail, positional accuracy
c.
this is undefined for digital data
The second problem (resolution is finite):
1) The earth’s surface is infinitely complex &
could be mapped to molecules/smaller
2 2)
Praxis determines the most largest (usually most
relevant) features
a.
This
makes me wonder why the largest features are usually most relevant
The third problem (resolution in processes):
a) If the process is significantly influenced by
detail smaller than the spatial resolution of the data, then the results of
analysis/modeling will be misleading (this is the problem of downscaling which
geostatistics seeks to alleviate through the use of an inferred correlogram)
a.
This
leads me to wonder if there are any processes that require all sorts of
different levels of scale
b) Most theories are scale-free
a.
can’t tell whether the model’s error (all models
are imperfect) is due to spatial-resolution effects or the model, or both
There are two methods for conceptualizing geomorphological
phenomena, which are scale-independent theoretical frames:
1) Discrete objects
a.
the world’s surface is empty like a table top (it is empty in the sense of it being simply
flat, not empty empty or without a
coordinate system) except discrete things
b.
things can overlap
c.
good for biological organisms, vehicles,
buildings
d.
represented as points, lines, areas, volumes
e.
so these
would be better able to map interactions between things (even if those things
are not things per se), where in the
continuous-field this would be lost/aggregated/generalized, esp. raster models?
f.
maybe we
can make a partial analogy between this and substance ontology?
2) Continuous-field
a.
phenomena expressed as mappings from location to
value/class, so every location in space-time has exactly one value of each
variable
b.
topography, soil type, air temperature, land
cover class, soil moisture
c.
process
ontology?
Both of these can be raster or vector data, but raster can’t
be laid on curved surfaces
1)
Raster data has resolution explicit in the size
of its cells
a.
smaller cells, more of them = better resolution
b.
the intervals between samples defines this
c.
in 3-d sampling the vertical dimension is often
sampled differently than the horizontals leading to a differential in
resolution
i. e.g.
remote-viewed 2-d map + field photos of vertical dimension
2)
Vector resolution is poorly defined and
difficult/impossible to infer a posteriori from the contents of its data sets
(as most GIS work is done on already present data sets)
a.
if the data’s taken at irregular points the
distance between points may be used as resolution – how often is the data taken irregularly?
i. use
the minimum, mean, max nearest-neighbor distance?
b.
when data’s captured as attributes of areas,
it’s represented as a polygon/polyhedra
i. resolution
is the infinitely thin boundaries, density of sampling of the boundary,
within-area/volume variation that’s replaced by homogeneity, size of
areas/volumes
ii. this
creates the impression that vector data has infinite resolution
1.
at finer resolutions the numbers of
areas/volumes increase and their boundaries are given more detail but they’re
more homogeneous
GIS encounters a problem that applies to many types of geographic
data
-measuring the length of a digitized line
-a vector polyline’s length is
easily computed as the sum of straight-line segments
-if we assume each sampled point
lies exactly on the true line, we will get an underestimate of the truth
because no line has the points lie exactly straight
-the
underestimate is by an amount that depends on sampling density
-this applies to all natural
features, slope, land cover
-this reminds me of stats (line regression) and calc (instantaneous
velocity)
-the issue of zooming out and losing detail/generalizing reminds me of
“essentialism” from philosophy, & i’m sure the problem of definition comes
up elsewhere in GIS (what variables to use, what sampling method)
-the modified area unit problem shows us that aggregation or
intersections of mapping elements (data collection and state lines, for
example) will change correlations in a manner that is not random variation from
alternative samples
-mandelbrot tells us that the rate of info loss/gain is
constant/predictable through scaling laws and exhibits power-law behavior and
self-similarity
an image displaying self-similarity:
-geostatistics gives us spatial interpolation to refine the
spatial resolution of a point data set artificially through methods such as
spatial autocorrelation, correlograms, and variograms
when creating an inferred correlogram does one infer up in levels/”steps”
till the desired resolution of the study?
-wavelet analysis (a subset of Fourier analysis) allows the
decomposed field variables to vary spatially in a heirarchical fashion – this sounds very interesting
In light of all of this, I am currently
wondering about the study of part-whole interactions in relation to resolution
and vector/raster datasets.
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