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 next week 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 maplayer1with maplayer2with maplayer3 ;

Cover1

2

3

Newmap

Newmap = Cover maplayer1with maplayer2with maplayer3 ;

Cover operationmosaic statement format

Newmap = Cover maplayer1with maplayer2mosaic ;

1

2

Cover mosaic

Newmap

Newmap = Cover maplayer1with maplayer2mosaic ;

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 ;Existingvalue is a number from the legend of the oldmap

Recode modifiersnewmap = Recode oldmap

Assigning newval To existvalAssigning newval2 To existval2…

existval3Assigning 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 operationstatement format

Newmap = Slice inputmap into value ;

modifiers of Slice

Newmap = Slice inputmap into value

by value range

value range use topvalue use middlevalue

use bottomvaluemakerangelabels ;

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 actionWhat will be grouped if we run clump at a distance of …

1 ?

1.5 ?

3 ?

Clumped at distance 1

Before After

Clumped at distance 1.5

Before After

Clumped at distance 3

Before After

Another new item:The Count function

Valuefield

Areafield

This function produces a new map where the number of cells in each zone in the old map becomes the value for that zone in the new map. It measures Zone Area

The Count in action

NewMap = Count (inputmap) ;

Inputmap Legend New Map Legend

• The binary number system is commonly used in computer science applications. We often use it in GIS.

• Map examples:– Rural or Urban zones– Man made or Natural– Land or Water areas

Binary Maps

• Both mask maps and binary maps have only 2 zones.

• Binary maps are typically something and something else

• Mask maps are something and VOID

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