Week of Jan. 15
Today’s agenda:
Announcements & reminders
MFworks operations
Give out assignment#2
Continue work on assignment#1
Announcements & Reminders
Still working on the printers
Assignment #1 is due in two weeks at the beginning of the lab
Assignment #2 will be due week of Feb.5
Lab Supervisor orientation meeting this Thursday afternoon (Jan. 18)
Does anyone need help formating a PC Zip disk for the Mac?
Important raster GIS concept
Data is numeric
Operations work on the data not the map colours
MFworks operations and functions
Cover
Recode
Slice
Spread
Clump
Count function
Operation Taxonomy
Group 1: Basic operations on 1 Layer
Explicit renumbering (= Recode)
Automatic renumbering (=Slice)
Basic measurement (=Spread)
Adjacency assessment (=Clump)
Group 2: Basic operations on n layers
Layer superimposition (=Cover)
Cover operation
A Group2 operation: Layer Superimposition
The Cover operation is used for two main purpose:
1) overlaying map layers
2) for mosaicking map layers
Cover operation
overlay statement format
Newmap
= Cover maplayer1
with maplayer2
with maplayer3 ;
Cover
Cover operation
mosaic statement format
Newmap
= Cover maplayer1
with maplayer2
mosaic ;
Recode operation
- A Group 1 operation: Explicit Renumbering
- Generates a new map layer
- You specify the zones from the input map that will appear in the output map
- Use the "…" operator for specifying number ranges (from the keypad menu in the script window)
Recode statement format
newmap
= Recode oldmap
Assigning newvalue To existingvalue ;
Recode modifiers
newmap
= Recode oldmap
Assigning newval To existval Assigning newval2 To existval2…existval3
Assigning newval3 To existval4 … Assigning newval4 To … existval5 Assigning newval5 To …
CarryOver ;
Slice operation
A group 1 operation: Automatic Renumbering
Slice may be thought of as an "automatic" recode
The concept of "Slice"
It divides the range of values in an input map into equal sized groups
Each group becomes a zone in the output map
An example of the Slice in action Here is a map
The legend for this map looks like this
The same map after being sliced into 5
The resulting legend has only 5 zones
Slice operation
statement format
Newmap
= Slice inputmap into value ;
modifiers of Slice
Newmap
= Slice inputmap into value by value range value range use topvalue use middlevalue use bottomvalue makerangelabels ;
Spread operation
A Group 1 operation: Basic Measurement
Measures distances from specified cells
Spread statement format
newmap
= Spread oldmap
To maximum distance ;
Spread will measure the distances starting from any non-void cells in the input map.
Clump
A Group 1 operation: Adjacency Assessment
"Clump" is used to group together or join together cells
From the MFworks guide: "The Clump operation creates a map layer in which cells with the same value, within a specified distance of each other, are assigned a common unique value."
Format of the Clump operation
NewMap
= Clump inputmap at Distance ;
The Clump in action
Clumped at distance 1
Clumped at distance 1.5
Clumped at distance 3
Another new item:
The Count function
Value
field
The Count in action
Binary Maps
A mask map is a special type of binary map
When to use masks
Masks are used to restrict GIS operations to a specific area
Masks are used to ‘blot’ out areas or regions in a map
Assignment #2
Gain experience working with Basic Operations (I and II) as they are implemented in MFworks
Also develop
Scripting skills
Spatial processing
Cartographic layout and design
Problem solving
2 part assignment
Part 1 - work on Spatial Relations. Measuring distances and areas
Part 2 - concept of Competing Distances and cartographic visualization.
Advice
Work on this assignment on your own
You will get more out of it if you try to develop your problem solving skills
You will need the experience with writing scripts and the concepts of the operations when it comes to exam time
Read over the entire assignment before beginning it
Familiarize yourself with the structure of it
Note the section at the back on output tips and try to apply them to your layouts
Things to remember from last week
Keep your files organized - make an Assignment#2-yourname folder for this assignment
That’s all
Use the time to finish up Assignment #1 and maybe start Assignment #2
The lab should be open starting next week for drop in work sessions