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Pictures and images of Johannesburg
taken by its corporate geo-informatics unit are a mine of useful information
for developers and ordinary citizens alike.
AERIAL photographs of
Johannesburg were on display at Metro Centre, and it seems geographic information
systems (GIS) maps are better than their Google Earth counterparts.
Aerial shot of Soccer City (Courtesy: Lesley Adams, CGIS)
The pictures and oblique
imagery of the city, taken in May, were exhibited by the City's corporate geo-informatics
(CGIS) unit on GIS Day, marked worldwide on 18 November.
Comparing GIS maps and Google
Earth, a senior GIS specialist, Deena Naidoo, said: "Google Earth's images are
more distorted, and the dates on the images are not necessarily the specific
date the photo was taken ... GIS shots are clearer due to the high [resolution] photography,
and it gives a new dimension, as users can also view buildings from different
angles and different vantage points.
"They also don't have the colour
band seen on Google Earth," he said.
Staff from the City unit was
clearly visible in their orange T-shirts, explaining GIS to visitors to the
Metropolitan Centre in Braamfontein.
GIS Day is important to
create awareness of GIS and to get customer feedback. "It's a two-way thing; we
use customer feedback to adapt the website and to produce better products for
them," said Marcelle Hattingh, the director of CGIS.
Much information on GIS was
available at stands at Metro Centre, and aerial photography and oblique imagery
of Johannesburg were exhibited.
"The aerial photography was
taken in May this year and covered every part of Johannesburg ... The attention
to detail on the photography is very useful, especially to developers,"
Hattingh explained.
GIS software represents
features on the Earth such as buildings, cities, roads and rivers on a
computer. GIS can be used to visualise, analyse and understand this data about
the world and human activity. The data are often viewed on maps, patterns are
revealed that may not be apparent in tables or databases. This is called the geographic
advantage.
GIS can also be used to map
dynamic events such as a hurricane or the spread of a disease outbreak. In Joburg,
businesses can map demographic data to learn more about their customers.
"Users can switch between the
data sets using change detection to compare the changes of an area through the
years," Naidoo said during the viewing of the aerial photography and oblique
imagery. "GIS is especially important for planners, as they can measure heights
of buildings using the area measuring tool, and can calculate the amount of
paint to use for a specific building."
"It is important for us
[CGIS] to remain updated technologically wise," Hattingh said. "Quality [of
photography] is extremely important to us - we are currently busy with quality
assurance."
GIS makes map data
interactive and more useful. It shows a street as more than a screen graphic. For
example, when looking at a street on a GIS map, detailed information is
available such as speed limit, number of lanes, the last time it was paved, any
planned construction, and a multitude of additional related facts that give an
accurate understanding of the street.
"The [CGIS] website is open
to the public. Anyone can get information ranging from zoning to street address
on the site," said a CGIS specialist, Lungile Nkosi. The site, run through
Joburg's Eservices,
has a free access section where people can get basic information on stand
numbers, street addresses, planning and so on.
There is also a subscription
site with additional information, including customised mapmaking tools, area
and distance measuring, and detailed zoning information. Subscription access
ranges in cost from R110 for individuals to R550 for businesses, per month.
"There is also free website
training
available,"
Nkosi added.
Mavela Dlamini, the City manager,
was also present at GIS Day during the viewing of the aerial photography and
oblique imagery, and believes anyone can benefit from using GIS. "Learners,
architects, developers - anyone can benefit from this," he commented.
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