NCAR Graphics
Contouring and Mapping Tutorial

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May 1993

This documentation is subject to the terms and conditions specified in a valid, executed License Agreement between Licensee and Licensor.

Published by: National Center for Atmospheric Research, Scientific Computing Division, P.O. Box 3000, Boulder, CO 80307-3000. The National Center for Atmospheric Research is operated by the University Corporation for Atmospheric Research and is sponsored by the National Science Foundation. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Trademarks: All brand and product names are trademarks or registered trademarks of their respective holders. Reference to a company or product name does not imply approval or recommendation of that company or product to the exclusion of others.

Printed on recycled paper (25% post-consumer waste).

Acknowledgments

Author

Adrianne Middleton-Link

Technical writer/editor

Brian Bevirt

Artist

Jacque Marshall

Document production

Christine Guzy, coordinator
Jacque Marshall

Technical reviewers

Ethan Alpert, SCD

Donna Beller, CGD

Michael Böttinger, Deutsches Klimarechenzentrum GMBH

Ginger Caldwell, SCD

Lee Carter, SCD

Diane Chace, Fleet Numerical Oceanography Center

Fred Clare, SCD

Dennis Colarelli, SCD

Nancy Dawson, SCD

Jim Eenigenburg, U.S. Forest Service

Keith Eggleston, Northeast Regional Climate Center

Gabor Fichtinger, Center for High Performance Computing, University of Texas at Austin

Christine Guzy, SCD

Mary Haley, SCD

Ken Hansen, SCD

Evelyn Hesse, Fleet Numerical Oceanography Center

Dave Kennison, SCD

Jeff Kuehn, SCD

Kirk Maasch, Quaternary Institute, University of Maine

Jacque Marshall, SCD

Pete Morreale, SCD

Tom Parker, SCD

Juli Rew, SCD

Tim Scheitlin, SCD

Dennis Shea, CGD

Susan Smith, SCD

Shirley Stephan, Lawrence Livermore National Laboratory

Paula Theophilus, SAIC

Michael Timlin, CIRES

The author especially wants to thank Dave Kennison of NCAR's Scientific Visualization staff. Dave has provided extensive technical support, explanations, and suggestions for this tutorial.

Thanks to Christine Guzy for pioneering many new techniques for electronically producing all the graphics in this book and demonstrating new ways to publish NCAR Graphics output. This work was made possible by ongoing technical support from Fred Clare, Dave Brown, John Clyne, and Dave Kennison of the Scientific Visualization Group. Thanks to Martha Lankton of NCAR Graphic Services for her help in printing this manual.

The instructional design principles used in this manual were planned by Adrianne Middleton-Link, Jeff Kuehn, and Brian Bevirt; the design was executed and refined by Brian Bevirt and Jacque Marshall. This particular design is derived primarily from seminars and books by Edmond H. Weiss, Ph.D.

Special thanks to Jacque Marshall for using Adobe Illustrator to create all the illustrations in this document that were not produced with the NCAR Graphics package. Jacque has also developed and and refined the templates for this design using Microsoft Word and FrameMaker.

Conventions used in this document

General

Bold type indicates filenames, pathnames, directories, UNIX command names, and UNIX command line options. The files that provide examples for this tutorial are sometimes specified by their exact filename, and other times the usage is more informal. Examples:

Using ccprwc.f, set RWC=100, then set RWC=250, and compare the plots for differences.
Using the ccpcit example, set Conpack so that every third contour is labeled.

Italic type indicates a variable where you provide the substitution. For example:

The example uses "nice" values based on n/3*10k, where 1<=n<=11, and k is any integer.

Fortran

Fortran code segments and error messages are shown in Courier ("typewriter") font:

  CALL GRIDAL (K-1, 0, N-1, 0, 1, 1, 5, 0., 0.)
  ERROR    6 IN CPSPS2 - ERROR IN CALL TO MSSRF1

In the synopsis of Fortran code segments, lowercase letters represent a specific value that must be used in the code. These strings conform to the Fortran naming convention for declaring variable types as INTEGER or REAL. Examples:

  CALL CPSETI ('PAI', n)
  CALL CPSETR ('CIT', cit)
  CALL CPGETI ('LIU', liu)
  CALL CPSETI ('RWC', irwc)

When a line of Fortran code is longer than the width of the column, the continued line is indicated with a plus sign (+) in Fortran column 6. Example:

  4       IF (IDLS .NE. 1 .AND. IDRS .NE. 1 .AND.
         + IDLS .NE. 3 .AND. IDRS .NE. 3 .AND.
         + IDLS .NE. 11 .AND. IDRS .NE. 11 .AND.
         + IDLS .NE. 79 .AND. IDRS .NE. 79 .AND.
         + IDLS .NE. 99 .AND. IDRS .NE. 99 .AND.
         + IDLS .NE. 104 .AND. IDRS .NE. 104 .AND.
         + IDLS .NE. 107 .AND. IDRS .NE. 107 .AND.
         + IDLS .NE. 163 .AND. IDRS .NE. 163) NPTS=0
  5       RETURN
  6       END

SCD documentation and consulting

Ordering information

For ordering information, please contact NCAR Graphics ordering information at (303) 497-1201 or scdinfo@ncar.ucar.edu or

University Corporation for Atmospheric Research
SCD/NCAR Graphics Orders
P.O. Box 3000
Boulder, CO 80307-3000 (USA)

How to get consulting help

If you have questions about using NCAR Graphics, contact your NCAR Graphics site representative. If you do not know who your site representative is and cannot find out from other users or the package installer at your site, you can call the NCAR Graphics Information Line at (303) 497-1201 to obtain the name of your representative. In its sole discretion, NCAR provides limited consulting support on usage and installation on an "as available" basis only. (Please refer to your Software License Agreement for a complete definition of "support.")

NCAR Graphics Contouring and Mapping Tutorial

Intro 1. A short introduction 1

Purpose of this tutorial 1

Design of this tutorial 1

Other resources to use with this manual 1

Intro 1.1 Understanding the layout of tutorial modules 2

Intro 1.2 Details about how information is presented in this manual 4

Reference guides throughout 4

Basic concepts explained first 4

Instructions for performing tasks 4

Using Areas

Ar 1. What is Areas? 9

Ar 1.1 Table of Areas user entry points 10

Initialization and support routines 10

Action routines 10

Query routine 10

Parameter setting and retrieving routines 10

Debugging routine 10

Ar 1.2 Table of Areas parameters 11

Ar 1.3 Areas definitions: Edges 12

Ar 1.4 Areas definitions: Groups of edges 14

Ar 1.5 Areas definitions: Left and right 16

Ar 1.6 Areas definitions: Areas, area identifiers, and area maps 18

Ar 1.7 Areas definitions: Masks and areas defined by more than one edge group 20

Ar 1.8 What calls do I need to get my Areas plot? 22

Ar 1.9 Areas parameters: What they do and how to use them 23

Ar 2. Initializing Areas 25

Ar 2.1 Set up area map 26

Ar 2.2 Adding edges to an area map 28

Ar 2.3 Preprocess area map: Overview 30

Ar 2.3.1 Preprocess area map: Breaking up edges 32

Ar 2.3.2 Preprocess area map: Removing coincident and dangling edges 34

Ar 2.3.3 Preprocess area map: Reconciling area information 36

Ar 3. Producing results using Areas 39

Ar 3.1 Obtaining area ids and group ids 40

Ar 3.2 Masking and drawing lines through an area map 42

Ar 3.3 Writing a masking or line-drawing routine 44

Ar 3.4 Filling areas 46

Ar 3.5 Writing an area-fill routine 48

Ar 4. Debugging Areas 51

Ar 4.1 Debugging options: Setting parameters 52

Ar 4.2 Debugging options: Drawing parts of the area map 54

Ar 5. Areas parameter descriptions 57

Using Ezmap

Mp 1. What is Ezmap? 63

Mp 1.1 Table of Ezmap user entry points 64

Single-call entry point 64

Map initialization routines 64

Latitude, longitude, and limb line drawing routines 64

Labeling routine 64

Map drawing and control routines 64

Positioning routines 64

Point and line routines 64

Color function 65

Inverse transformation routine 65

Parameter routines 65

Mp 1.2 Table of Ezmap parameters 66

Mp 1.3 Table of Ezmap map projections 67

Mp 1.4 Description of projections: Conic 68

Mp 1.5 Description of projections: Azimuthal 70

Mp 1.6 Description of projections: Cylindrical 72

Mp 1.7 Producing a quick and dirty plot 74

Mp 1.8 What calls do I need to get my Ezmap plot? 78

Mp 1.9 Ezmap parameters: What they do and how to use them 79

Mp 2. Getting set up 81

Mp 2.1 Positioning the plot in the frame 82

Mp 2.2 Choosing your map projection 84

Mp 2.3 Choosing your map projection: Satellite view 86

Mp 2.4 Choosing map outlines to be drawn 88

Mp 2.5 Setting limits for the projection 90

Mp 2.6 Setting map line colors 94

Mp 2.7 Controlling Ezmap lines 96

Mp 2.8 Controlling geographic and political outlines 98

Mp 2.9 Rectangular and elliptical perimeters 100

Mp 2.10 Saving and retrieving Ezmap parameters 102

Mp 3. Simple maps 103

Mp 3.1 Initializing Ezmap 104

Mp 3.2 Grids: Drawing latitude and longitude lines 106

Mp 3.3 Grids: Dash patterns 108

Mp 3.4 Labeling 110

Mp 3.5 Drawing political and geographic outlines 112

Mp 3.6 A shortcut 114

Mp 4. Producing maps with masking or filled areas 117

Mp 4.1 Color and area identifiers in Ezmap 118

Mp 4.2 Ezmap group identifiers 120

Mp 4.3 Initialize Ezmap with Areas 122

Mp 4.4 Labeling 124

Mp 4.5 Grid lines with masking 126

Mp 4.6 Grid lines with masking: Writing a masking routine 128

Mp 4.7 Filling areas 130

Mp 4.8 Filling areas: Writing a fill routine 132

Mp 5. Points, lines, and inverse transformations 135

Mp 5.1 Projecting a point onto the map 136

Mp 5.2 Inverse transformations 138

Mp 5.3 Drawing lines on a simple map 140

Mp 5.4 Drawing a great circle between two points 142

Mp 5.5 Adding lines to an area map 144

Mp 5.6 Drawing lines masked by an area map 148

Mp 6. Table of Ezmap area identifiers 153

Mp 7. Ezmap parameter descriptions 169

Using Conpack

Cp 1. What is Conpack? 179

Cp 1.1 Table of Conpack user entry points 180

CONREC simulation routines 180

Conpack initialization and data support routines 180

Background routine 180

Labeling routines 180

Contour line drawing routines 181

Parameter access routines 181

Cp 1.2 Table of Conpack parameters 182

Cp 1.3 Producing a "quick and dirty" plot 190

Cp 1.4 More complex black and white plots 192

Cp 1.5 What calls do I need to get my Conpack plot? 196

Cp 1.6 Conpack parameters: What they do and how to use them 198

Cp 2. Backgrounds for your plots 201

Cp 2.1 Generating a background 202

Cp 2.2 Drawing a contour perimeter 204

Cp 2.3 Setting X/Y axis values for a contour background 206

Cp 2.4 Changing perimeter options 208

Cp 2.5 Labeling X/Y axis values for a contour background 210

Cp 2.6 Contour perimeter: Size, shape, and location using Conpack 214

Cp 2.7 Contour perimeter: Size, shape, and location using SET 216

Cp 3. Initializing Conpack 219

Cp 3.1 Data types 220

Dense gridded data 221

Sparse gridded data 221

Irregularly spaced gridded data 221

Nongridded data 221

Missing data 221

Non-Cartesian data 221

Cp 3.2 Dense gridded data 222

Cp 3.3 Sparse gridded data 224

Cp 3.4 Irregularly spaced gridded data 226

Cp 3.5 Nongridded data 230

Cp 3.6 Missing or special data 234

Cp 3.7 Non-Cartesian data 236

Cp 3.8 Non-Cartesian data: Latitude/longitude data 238

Cp 3.9 Non-Cartesian data: Polar coordinates 242

Cp 3.10 Non-Cartesian data: Other data types 244

Cp 3.11 Contouring non-rectangular domains 246

Cp 3.12 Setting minimal workspace 248

Cp 4. Contour line basics 251

Cp 4.1 Contour line basics 252

Cp 4.2 Drawing contour lines 254

Cp 4.3 Four methods of contour level selection 256

Cp 4.4 Default contour level selection 258

Cp 4.5 Default contour level selection: Default intervals and labels 260

Cp 4.6 Default contour level selection: Fixed contour intervals and labels 262

Cp 4.7 Modifying Conpack-chosen levels: Picking levels 264

Cp 4.8 Modifying Conpack-chosen levels: Changing the levels 266

Cp 4.9 Setting n equally spaced contour levels 268

Cp 4.10 Choosing your own contour levels 270

Cp 4.11 Line attributes: Line dash patterns 272

Cp 4.12 Line attributes: Line thickness 276

Cp 4.13 Line attributes: Line color 278

Cp 4.14 Line attributes: Turning contour line drawing off and on 280

Cp 5. Filling contour levels 283

Cp 5.1 Area identifiers in Conpack 284

Cp 5.2 Group identifiers in Conpack 286

Cp 5.3 Initialize Conpack with Areas 288

Cp 5.4 Adding label boxes to the area map 292

Cp 5.5 Masking areas: Label boxes 294

Cp 5.6 Masking areas: Box masking routines 298

Cp 5.7 Filling contour levels 300

Cp 5.8 Filling contour levels: Writing a fill routine 304

Cp 6. Contour line labels 307

Cp 6.1 Annotating your plots 308

Cp 6.2 Forcing labels to be chosen 310

Cp 6.3 Selecting lines for labels: Default method 312

Cp 6.4 Selecting lines for labels: Labeling every nth line 314

Cp 6.5 Selecting lines for labels: Labeling specific lines 316

Cp 6.6 Three methods of label placement 318

Cp 6.7 Label placement: Default method 320

Cp 6.8 Label placement: Regular scheme 322

Cp 6.9 Label placement: Penalty scheme 324

Cp 6.9.1 Label placement: Penalty scheme---Gradient term 326

Cp 6.9.2 Label placement: Penalty scheme---Crossing contours 328

Cp 6.9.3 Label placement: Penalty scheme---Tight curves 330

Cp 6.9.4 Label placement: Penalty scheme---Label spacing 332

Cp 6.10 Label attributes: Angle and orientation 334

Cp 6.11 Label attributes: Color 336

Cp 6.12 Label attributes: Label text options 338

Cp 7. General labels 341

Cp 7.1 Overview of labeling in Conpack 342

Cp 7.2 Titles 344

Cp 7.3 Numeric control: Significant digits 346

Cp 7.4 Numeric control: Formatting 348

Cp 7.5 Numeric control: Exponents 350

Cp 7.6 Label attributes: Angles 352

Cp 7.7 Label attributes: Size 354

Cp 7.8 Label attributes: Constant field and information text 356

Cp 7.9 Label attributes: High/low text 358

Cp 7.10 Label attributes: Color 360

Cp 7.11 Label box attributes: Outline and fill 362

Cp 7.12 Label box attributes: Line width 364

Cp 7.13 Label box attributes: Size 366

Cp 7.14 Label placement: Constant field and information labels 368

Cp 7.15 Label placement: High/low 370

Cp 7.16 Constant field found flag 372

Cp 8. Overlaying filled contours on a map 373

Cp 8.1 Initialization 374

Cp 8.2 Masking areas: Label boxes and land masses 376

Cp 8.3 Filling specific contour and geographic areas 378

Cp 8.4 Filling areas: Polar projection 380

Cp 9. Advanced topics 383

Cp 9.1 Smoothing contours 384

Cp 9.2 Hachuring: Indicating slope on a contour plot 386

Cp 9.3 Cell arrays 388

Cp 9.4 Making a movie 390

Cp 10. Conpack parameter descriptions 393

Index 419

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