In cartography there are two basic types of maps, general purpose maps and thematic maps. General purpose maps emphasize location. They display a variety of features, that can be naturally occurring or man-made. A thematic map or special purpose map, shows variance and characteristics of data with a geographic distribution. Simply it shows the differences and relationships between data. These maps should contain several elements to help ensure accuracy and clarity. These elements include: projection, scale, north arrow and a legend. Additionally a thematic map will also contain a color selection and data classification. Cartographic generalization is an important part of the map design process. In this process a cartographer chooses which map details need to be preserved and which will be distorted. A map can only display so much before its purpose is lost. It is the job of the cartographer to find a balance between the maps purpose and real world representation.
From the prehistoric Lascaux Cave drawings of 15000 BC, to the Greek geographer, mathematician and astronomer, Eratosthenes of 2200 BC, people have been exploring and recording the world around them. Famous explorers and cartographers like James Cook have left a legacy of geographical knowledge which, even today, influences the way we view our world. So what is cartography and why has it developed throughout the ages? In its most basic form Cartography is simply the art of map making, but those who delve a little deeper understand that the subject is more intricate then anticipated. Maps provide a vast resource of information, they are research tools to aide in informed decision making and function as historical documents offering a window into the past. As times change so has the discipline of cartography. Advancements in technology has sparked growth in the industry and, as the benefits of visual data analysis are recognized, people are finding new ways to leverage these resources. In order for cartographers to produce effective maps they must not only focus on map making and design but also have an understanding of how maps are being used. As we continue to move towards a data driven society, maps are playing a key role in displaying data as useful and comprehensible information. They have become part of the communication process, the sharing of information between the map maker and the map user.
Python is an efficient and effective object oriented programing language which runs in a number of environments including: Windows, Linux/Unix, Mac OS X, and has been ported to the Java and .NET virtual machines. It is the Language of choice for ArcGIS applications and is extremely helpful for simplifying and automating a variety of tasks. For a better understanding try the ArcGIS resource – Python for ArcGIS. It contains helpful links to blogs, forums, communities and videos to get you started with Python programming. Like learning any new language Python can be challenging but its benefits greatly outweigh is frustrations so stick with it.
This is some simple Python code generated by ArcMap’s model builder and altered to run in an Integrated Development Environment (IDE)
#This code adds a buffer to a selected set of roads.
arcpy.env.workspace = “directory path ”
arcpy.env.overwriteOutput = True
#Set parameters used to join the BufferDistance table to the Roads feature class
inFeatures = “Roads”
inFields = “ROUTE_TYPE”
joinTable = “BufferDistance”
joinField = “ROUTE_TYPE”
#Join table to feature class
arcpy.JoinField_management(inFeatures, inFields, joinTable, joinField)
#Set parameters used to buffer Roads feature class
outBuffers = “RoadsBuffers”
buffField = “DISTANCE”
#Buffer the roads based on DISTANCE attribute
arcpy.Buffer_analysis(inFeatures, outBuffers, buffField)