Intermediate Operations — Neighborhood Filtering

MF works Colorization

• Conclusion of the sub-unit on Cartographic Visualization

MFworks Colorization — of a single layer

Single color

Color sequences — “paths”

• monochome
• linear RGB (2-color sequence)
• multichrome
• composite sequences: series or sets of sequences

Color Class Schemes: Sequential, Zone Value, Zone Area

Examples of paths used by cartographers (and GISers)

Layering

Why layer?

Separating

• The challenge of separating

Rules for using color

Background -

• muted
• maintaining unity (intermingling when necessary)

Foreground (“Figure”)

• bright spots of highly saturated color
• color combinations to avoid

Use the colors found in nature

• especially gray

Match colors with what they are representing:

• color as labels, measure, imitation of reality, decoration

“L&S” graphic design issues (Do’s and Don’ts)

Dark grid lines are “chartjunk”

• grids should be muted (eg. by using few, thin gray lines)
• or discard the grid leaving behind an implicit grid

“felicitous subtraction of weight

• enhances representation of both data dimensionality and density on flatland...”

the effectiveness and elegance of

• small spots of intense, saturated color for carrying information
• —a design secret of classical cartography. and for that matter of traffic lights.

Graphic types of overlays

• points, lines and areas
• draping over a landscape surface
• translucence (and highlights as a special case)

Layering tools

• transparent overlay (and masking)
  • using Recode and Cover
• translucent overlay
  • using Arithmetic

Layout

• Elements: Title, Border, Scale, North Arrow, Rulers/Grids, Legend, Annotation
• Use of Space: Empty space, layout, multi functioning graphic elements, redundancy, non-data ink
• Map Size: size matters! sheet size, magnification technologies: raster plotters, xerography, photography, multi-sheet series

Announcements:

Upcoming Lectures (after slack week)

• March 2: Guest Lecture by Prof. Jinfei Wang
• March 9: Mid Term Exam
• March 16: Lecture by Dr. Pazner
  • (in lieu of GIS 2000)
  • Catch Up and Other topics
  • e.g. DEM, Terrain analysis and visualization

GIS 2000 Report

• We now stand at a 14 participants from UWO Geography
• and climbing

The date for the final exam: Tuesday April 24, 7-9 PM

Reading Corner

• Chapter 4: Getting the Map Into the Computer
  • Questions? Discussion? ....
  • Reading Assignments:
• Chapter 7: Making Maps with GIS
  • part of Mid Term Material
• Chapters 8 (How to Pick a GIS) and 10 (The Future of GIS)
  • in the 2 weeks after the Mid Term, and
  • by the Lecture on Thursday March 23

Ombudsmen Meeting Report: Student Issues and Instructor’s Responses

• "Can Assignment 3 due date be postponed?"
  • Unfortunately not.

"Request for making lecture notes available beforehand (before the lectures)."

• Fortunately Yes...Consider it done

"It’s hard to get a handle on Lecture material and Labs"

• This material tends to be confusing at first and then becomes more clear.

Instructor’s Notices:

Explanation Corner: "Confusing Issues"

• in small groups, make a list to the instructor stating what was the most confusing aspect of the explanation of a topic or point in one of the lectures
• (if you can’t agree on only one, rank them)
• write your names and submit a copy to me

Stumped in Lab?

• Work with class mates, ask TA , instructor during office hours or by appointment.

System problems in Lab:

• Notify Lab Supervisor — have them fill out a Problem Report form and pass it to the Lab Coordinator
• Bring it to my attention — I am very interested.

The Structure of Today’s Lecture:

• MFworks Colorization — mop up of this topic
• Mock MidTerm Exam
• Intermediate Ops. in brief:
  • Interpolation (Interpolate)
  • Neighborhood Filtering (Scan and Filter)

Mid Term Exam

• Sample Exam is here
• Exam is worth 25% of your mark
• Bring a calculator

The Theme of the Exam: "Good Command of the Basics"

• You are given a limited body of information,
• and are expected to demonstrate that you have it under control...
• Part I has one question and is worth 25 points (choice of 1 out of 3 questions)
• Part II has five questions and is worth 75 points (15 points per question choice of 5 out of 7 questions)

Scope of the exam:

• Readings from Chapters 1, 2, 3, 4 and 7
• Group I and Group II Operations (Intermediate Ops. not included)
• Essay tests the "Getting Started with G.I.S." readings

Use a micro/macro approach to learn the material

• macro: know the organization (structure) of the book, chapters, sections, main sub sections
• micro: know some of the details, e.g. bolded terms and (good) diagrams

Outline: a hierarchical list —

Short Problem Solving Problems test your Operations: understanding, mastery (problem solving)

Intermediate Operations on 1-2 Layers

General comments:

• We are moving into the less-commonly used groups of operations.

There is one common thread running through these operations

• The operations are truly spatial operations—
• they are sensitive to location on the cartographic plane (layer) and not just value.

These more spatial operations tend to be more complex

• and they have more spatial power.

Note that these operations are similar to Clump and Spread

• and unlike all the other operations we have come across thus far.

Spatial Interpolation — Interpolate

What it does: Fills in blank or ‘empty’ (VOID) cells with values calculated based on the surrounding values.

Behind interpolation is a whole, rich, subfield dealing with theory, methods, and algorithms.

Spatial interpolation must take two facets into account:

• spatial considerations and,
• magnitude-of-values considerations
• As a result both spatial sampling strategies and statistical computing strategies have to be devised and come into play.

An Example:

• Interpolating a dense DEM from sparse elevation data: either spot elevations or from contours.

A possibility with contour interpolation is to include auxilliary information such as maxima and minima (eg. ridge and channel data, and peaks and pits, cliffs, etc).

The parameters and the way they work:

In is used to specify a Mask map.

• Only the Void data map values that are at locations which corresopond to Non-void values in the Mask map will be interpolated.

To specifies the precision.

Within specifies the horizontal distance limit.

• Interpolate searches for the 1st closest value per octant.

Step specifies the coarsness of the 1st pass.

• Interpolate 1st only seeks to interpolate a coarse grid.
• The 2nd pass is exhaustive.
• This saves time and can produce better results.

Inverse Square applies a squared distance decay weighting scheme.

Neighborhood Filters —

• Scan and Filter