Geol 465 Intro to GIS Geographic Information Systems

Geol 465 - Intro to GIS Geographic Information Systems

Evaluation • Grades are based on two exams and completion of assignments in the lab part of the class • Midterm Exam is 22% of grade each • Final exam is 44% of grade • Labs are 34% of grade

Lab exercises • Software and hardware needed to complete lab exercises are available in this room (SC 3211) • Files needed to complete the exercises are available from the textbook, from me, or from a wide range of online sources

What is GIS? • A tool to be used by researchers • System involves collected, tabulated, processed, analyzed geographical data used to solve, diagnose or prevent problems • Maps are heavily utilized – Not the only means of portraying information – Differs from a CAD* system or a CAC‡ system • Arguably more powerful due to ability to generate DERIVATIVE data sets from pre-existing data * Computer Aided Design ‡ Computer Aided Construction

Subsystems for GIS • Data input and Preprocessing – Transformation of spatial data types • E. g. , from topo lines to elevation data points • Data storage and retrieval • Data manipulation and analysis – Modeling, simulations, estimates • Lloyd expressway example • Data reporting and display of information – Tabular, graph-based, or map based

Information systems Non-spatial Spatial Management systems Nongeographic CAD/CAM* *Computer Aided Manufacturing Geographic Info Systems Other systems LIS

Digital data • Has benefits over analog (non-digital) data – Photographic example – Rectification- alignment to coordinate system Unrectified Rectified

Digital data • Continuous data sets are not easily represented – Example topographic map data • Analog maps versus Digital elevation models

Topographic map grid

Same image as previous one, grid cells are shaded

Same image as previous two, just rotated to vertical

Georectified aerial and satellite photographs

Overlaying vector based maps to create derivative maps Color is attribute as is alphabetic designation

Layers of geographic information, which in turn can create new layers of data

Soils layer

Land Use Layer

Topographic layer

Watershed boundaries layers

Tiger file layer

Point specific layers Weather stations Point source pollution