Best Practices File Naming Conventions Files should not be named with spaces or any other special characters in its name. ▪ Multiple-band grid cannot.

Shawn L. Penman, PhD

GIS Tips, Tricks and Best Practices

DataBest Practices

Data Names are Everything File Naming Conventions

Files should not be named with spaces or any other special characters in its name. ▪ Multiple-band grid cannot have more than 9

characters in its filename, and a single-band raster dataset cannot have more than 13 characters.

▪ File geodatabase – file system limit▪ Feature class or table name – 160 characters▪ Field name - 64 characters

▪ Shapefile – file system limit▪ Field name – 8 characters

Geodatabase (10.1 +)

Rename and change the field’s types in the file geodatabase after the field has been created.

• Open the feature class properties in a file geodatabase, navigate to fields and you’ll find out that you can now rename them.

And if the table is empty, say when you’re working on creating a schema for an empty feature class, you can even change the type of the field (i.e. switch from FLOAT to DOUBLE). This means you can stop creating new

fields and using the Field Calculator to copy the values if all you need to do is just rename the field. Jump to the feature class properties dialog and rename it!

Copy/Moving GIS DataALWAYS USE ARCCATALOG

NEVER USE WINDOWS EXPLORER!!!

Data Movement

Data Organization

Plan on data acquisition and normalization to take 75% of the time on a project

Normalization can include: Clipping data to study area boundary Data model

▪ Vector Raster▪ Raster Vector

Projection▪ UTM… StatePlane…

File format▪ Shapefile Geodatabase▪ Coverage Geodatabase

Best PracticesDocumentation

Metadata

Data about Data! Metadata is crucial when using existing

data sources Federal standard (FGDC & ISO) It is located in different places and it

comes in different formats *.xml - XML *.txt, *.met – ASCII Text *.html, *.htm - Web

Metadata

Typical Metadata sections Identification Information

▪ Source Information▪ Date

Data Quality Information▪ Processing Steps (who did it? And What did they do?)▪ Date of Processing

Spatial Organization Information Spatial Reference Information

▪ Projection & Datum Entity and Attribute Information

▪ Definitions (what do those weird field names mean?) Distribution Information

▪ Can it be shared? Or is it for in house use only?

Why? Demonstrates professional integrity and data

credibility. Makes it shareable and publishable; very helpful for

team members and collaborators (federal, state, local, private) you share data with/to.

Provides ongoing history and archive of a data set. May make grant awards/opportunities more likely. Protects against loss of institutional data

knowledge.

Why Metadata?

Datasets Catalogued in Excel

Compliments of Rick Koehler at New Mexico Energy, Minerals, and Natural Resources

Data OrganizationVia folders, mix of file formats

Compliments of Gar Clarke at New Mexico Department of Information Technology

Data Folder Structure

Project Name Data Reports Mxds Maps Archive

Organization Standards

Standards Departmental Standards? Office Standards? Personal Standards?

Need to develop/maintain a strategy for organizing your data

What happens when a team member leaves for a new job?

Best PracticesProjections & Coordinate Systems

Why are coordinate systems important? Without a coordinate system (including a datum and projection) a

map is not a map but only a drawing. There are many different ones - each one is better for certain

purposes. Unfortunately, there is no single best system.

How does that influence a GIS project? The “best” systems depends on what you want to do and where

you are located. Data from different sources may be from different systems. Not knowing the system for data you are working with can create

major headaches! So, always make sure you know the system you are working with.

Why?

Why Datums are Important

Impact of incorrect assignment of datums

Bridge layer incorrectly assigned NAD 1927 (actually NAD 1983)Stream and road layer NAD 1927

A coordinate system that divides the 50 US states, Puerto Rico and the US Virgin Islands into more than 130 numbered zones

Developed in the 1930s to provide a common reference system to surveyors - to maintain accuracy, many states had to be divided in zones - the boundary of zones within states follow county boundaries

Units in feet or meters Each zone has its own projection, which may be cylindrical or conic:

Lambert conformal conic for zones that are longer east-wets (e.g. Kentucky) Transverse Mercator for zones that are longer north-south (e.g. Illinois) Oblique Mercator for zones at an angle (e.g. Alaska panhandle)

To specify a location, you need to report: (X,Y) coordinate pair State Plane zone Datum Units

State Plane Coordinate System

State Plane Zones

State Plane Zones - NM

West

Central

East

3002

30013003

Projection & Coordinate System Jeopardy

Troubleshooting unknown coordinate systems In ArcCatalog, select a geographic dataset and with the Properties dialog

box examine the coordinate system and extent. If the coordinates have values between -180 and +180 in the x-direction and -90 and +90 in the y-direction you likely have geographic coordinates. The next step is to identify the datum used for the data. Globally, WGS84 is the current standard datum. In the US, NAD 1927 is common on old datasets and NAD 1983 is common for new US datasets.

If the data shows an extent in which coordinates to the left of the decimal are 6, 7or 8 digits, the data is probably in a projected zone. Try UTM first and identify the zone by looking at a national UTM zone map.

If UTM doesn’t work, then try whatever is the local coordinate system. For example in the US try the local State Plane Coordinate System zone. Then determine the datum.

If you observe offsets from a few meters to several hundred meters, then you are possibly seeing a datum shift. In the US NAD 83 datum is approximately 200 meters north of the same data reference to the NAD27 datum. Source: Modeling Our World, second edition. Zeiler

& Murphy

Projection Best Practice

Matching The coordinate systems of all the layers should match

each other and should match the coordinate system of the data frame.

If layers are being projected on the fly, there may be unexpected alignment problems when making edits. 

ArcMap - A data frame maintains its own x, y tolerance, resolution, and domain values, which are taken from the first layer added to the map. Certain edits may fail, or features may collapse unexpectedly, because of the differences in these values between the data frame and the layers you are editing. 

Best PracticesCartography & Data Presentation

Purpose of Map?

Figure for report Map for irate citizen Map published on website Public zoning presentation Large format map Will the map be viewed close up or at a

distance Will the map stand alone, or will it be

part of a series of maps that share a similar design

Map Objectives

http://kitkatpecson.com/portfolio/work/a-map-of-ice-and-fire/

Design Objectives Highlight Relationships Illustrate results

Share Information Fulfill Intended Purpose

Map Message

Floodplain boundaries New subdivision boundaries City council districts and floodplain

boundaries Redistricting of districts after census

Map Production Checklist

Timeline for map production

Purpose of map Format & size of map

printer? Data availability Create Draft

possibly multiple drafts

QA/QC Map Legibility Communication

Make Revisions Non-GIS person review Deliver Final Product

Paper Electronic

Presentation Report Poster Oral

Type of MapBest method of communication

Single Symbol Map

http://moroccoonthemove.com/wp-content/uploads/2014/05/Africas-Hottest-Investment-Zones-2014-1024x975.png

Unique Values Map

Graduated Color Map

Graduated Symbol Map

Dot Density Map

Chart Map

http://www.bom.gov.au/water/ssf/faq.shtml

Multivariate Map

https://andersolson.files.wordpress.com/2012/09/multivariatemap.jpg

Data DisplayBest Practices

How Many Classes?

3

7

5

9

Maximum = 7 most map readers can distinguish up to 7 different colors

on a color ramp or gray scale, so more than 7 classes will make it difficult to identify features in the same class

more than 7 classes can be used for continuous data (e.g. elevation, temperature)

Minimum = 3 fewer than 3 classes will not show much variation

Strategy first determine the proper classification scheme than start with large number of classes reduce number stepwise and select the minimum number

of classes which still shows the spatial pattern in sufficient detail

Deciding How Many Classes

The values of the class should be meaningful 73.857 % is too detailed 73.9 or 74 % is probably OK 70% may not be detailed enough

You can use standard classification schemes but typically it is better to force rounding to a certain number of digits.

For example: 17386.346 17386.34 17386.3 17386 17390 17400 17000 20000

Making Classes Easier to Read

Changing Symbol Properties

Applying the same symbol to all values.

Change the default symbol first and then click add values. The symbol is the same for the added values.

Grouping Values

Select desired values, right click and selectGroup Values.

Map LayoutBest Practices & Tips

TALDOGS

T - TitleA - AuthorL - LegendD - DateO - OrientationG - GridS - Scale

This acronym will help you remember what to include on a map.

Source: South Carolina Geographic Alliance

Make title logical and succinct

On thematic map, include name of area and main subject

2010 Census Population, Bernalillo County, NM

T = Title

Organization or person who made map May want to include logo, department

and contact information

Prepared by:

A = Author

Explains map symbols Clear and legible

L = Legend

Date map was created or date of original data

You may have multiple dates for data and you could include this in the legend If you had DOQQ imagery from 2005 and

census data from 2010

D = Date

Maps in the United States are generally made with North at the top of the map and South at the bottom

Some specialized maps are oriented differently

Include a north arrow

O = Orientation

Please don’t use this one!

ArcMap can automatically put coordinate system grid around map

A “location map” (overview map) also works well

May not be necessary, evaluate the use on your map and decide what is best

G = Grid

Scale is a ratio that relates a unit of measure on a map to some number of the same units of measure on the earth’s surface.

S = Scale

Disclaimer

Does your office have one? RGIS.unm.edu

▪ The material on this site is made available as a public service. Maps and data are to be used for reference purposes only and the Earth Data Analysis Center (EDAC), Resource Geographic Information System (RGIS) and The University of New Mexico are not responsible for any inaccuracies herein contained. No responsibility is assumed for damages or other liabilities due to the accuracy, availability, use or misuse of the information herein provided. Unless otherwise indicated in the documentation (metadata) for individual data sets, information on this site is public domain and may be copied without permission; citation of the source is appreciated.

Ability to wrap text in legend! Legend Properties, Layout tab, Text

Wrapping.

Legend – ArcGIS 10.1

ArcMap will automatically add extent indicator ArcMap can also automatically generate

Leader lines, but it’s best to put those in by hand.

Extent Indicator

Add Extent Indicator in ArcMap Steps to inset Extent Indicator Go to Data frame properties and Extent Indicator

tab Decide which Data Frame will have Extent

Indicator. Right click on inset data frame, go to Extent

Indicator tab. Select main map and Click right arrow. Can change color and line thickness under Options, Frame.

If have multiple Extent Indicators you may want to use different colors to help viewer identify which Extent Indicator corresponds to which inset map

ArcMap Options

Can change whether youzoom in or out with scroll wheel on your mouse!

Set relative paths, so if you move your data ArcMap can find it again.

FEMA Map Service CenterTake advantage of someone else’s server

GIS Data

NFHL

Data Download

Download NFHL GIS Data

Web Services - Layers

Layers in the public NFHL GIS services:Use the numbers shown below when referencing layers by number.0. NFHL Availability1. LOMRs2. LOMAs3. FIRM Panels4. Base Index5. PLSS6. Toplogical Low Confidence Areas7. River Mile Markers8. Datum Conversion Points9. Coastal Gages10. Gages11. Nodes12. High Water Marks13. Station Start Points14. Cross-Sections

15. Coastal Transects16. Base Flood Elevations17. Profile Baselines18. Transect Baselines19. Limit of Moderate Wave Action20. Water Lines21. Coastal Barrier Resources System Area22. Political Jurisdictions23. Levees24. General Structures25. Primary Frontal Dunes26. Hydrologic Reaches27. Flood Hazard Boundaries28. Flood Hazard Zones29. Submittal Information30. Alluvial Fans31. Subbasins32. Water Areas

Web Services - REST

ArcGIS REST Service The ArcGIS REST service provides direct

access to NFHL spatial information through ESRI applications such as ArcGIS Desktop or ArcGIS Online. This service supports mapping, data, and query requests.

https://hazards.fema.gov/gis/nfhl/rest/services/public/NFHL/MapServer

Web Services - REST

URL

Web Services - REST

Can now add to ArcMap

Web Services – WMS & WFS

The NFHL Web Mapping Service provides an OGC-compliant protocol for obtaining map images and querying feature information.

Web Services – FEMA GeoPlatform

Web Services – FEMA GeoPlatform

PanelsLOMAs

GIS Help Desk

Do you have any GIS questions? I have ArcGIS, will answer questions!

Questions

Shawn L. Penman, PhD, CFM, [email protected](505) 277-3622 ext 227