Raster Tutorial ArcGIS 93

8/10/2019 Raster Tutorial ArcGIS 93

1/11

252886732.doc Page 1 of 11

Raster: The Other GIS Data

Objectives

Understand the raster format and how it is used to

model continuous geographic phenomena

Understand how projections & coordinate systemsaffect the outcome of geoprocessing tools

Know how to project raster datasets

Know how to use raster modeling to measure

distance

Know how to create Hillshade images

Know how to extract raster values to vector data

Know how to use the Surface

Know how to use Map Algebra to calculate new

raster layers from a set of raster variables

Know how to use the classification tool to reclassraster datasets

Know how to !lip" a raster dataset to a vector la

Know how to apply Symbology to a raster datase

Know how to create isometric contours from rast

data

Know how to resample raster data from one

resolution to another

The Raster Data Model

Surfaces are continuous geographic phenomena that cannot be described as discrete #eatures$" Surfaces are generally mods %aster" data of which the most familiar type is the digital photograph$ 'hings li(e elevation temperature slope andrecipitation have measurable values for any particular location on the earth"s surface$

'o model these phenomena an area of interest is divided into an array of identically si)ed s*uares$ 'he centers of these s*uahen become the sample points$" 'he values of the variable of interest are recorded or estimated at each of the sample point

'hese values can then be assigned colors or shades of gray in order for them to be visuali)ed$

'his tutorial will introduce you to some of the basic s(ills necessary to have when usraster data in your analysis$ 'his tutorial is in no way comprehensive rather it isintended to provide you with a base$

Getting Ready for the Tutorial

Sign Up for the GIS-L Listserv

'he +ale University ,-S./ /istserv is an internal University message systedevoted to ,-S use and issues at +ale$ 'he list is the primary source forupdates on software and license server issues data ac*uisitions andwor(shop announcements$ All ,-S users are encourages to sign up for th

list$ 'he ,-S./ list is very lightly used so that you will not beoverwhelmed with messages that are not relevant to you$

0$ -n your 1eb 2rowser Go Tothe Map Collection Websatwww$library$yale$edu3maps

4$ Under the Quick Linkssection on the right Clickon th5Sign up for the Yale GIS-L Mailing List6 lin( to go to ,-S./ registration page$

7$ Enteryour Email Aressand Choosea !ass"or$

The Yale Map Collection

At Sterling Memorial i!rar"13# $all Street% &oom 7#7

Stace" Maple' ( )*S A''i'tant

2#3+,32+826- 'tace".maple'/"ale.ed0.li!rar"."ale.ed0map'
http://www.library.yale.edu/mapshttp://www.library.yale.edu/mapshttp://www.library.yale.edu/maps


2/11

252886732.doc Page 2 of 11

Note: We suggest that you not select the Daily Digest feature.

8$ Clickon the Subscribe #uttonto finish$

You should receive a confirmation email shortly afterward, withinstruction on how to use the GIS- list.

Download the Data

'he datasets used in this tutorial are available for download on theMap !ollection 1ebsite$ #eel free to download and use theseutorial materials as you wish and to pass them along to interestedolleagues$

0$ Returnto the Map Collection $omepage in your Web#ro"ser$

4$ Under the Quick Links Sectionon the right Clickon the5%o"nloa GIS Workshop Materials6 lin($

7$ Findthe 5%ata6 Linkfor the Arc,-S 9$7 5&aster' (he )*ther+ GIS %ata6 and Right-Clickon the Link$

8$ -n ,irefo Select5Sa.e Link As6 in Internet Eplorer/Select5Sa.e (arget as06

:$ ;epending on your browser and setup you may be offered a #ro"se Wino" to select the folder into which you wanthe downloaded file placed$ -f so Browseto a ,oleron your hard drive that you have write permission for$ #or thistutorial we will assume that you are using the C'1temp folder of the machine you are wor(ing on$


3/11

252886732.doc Page 3 of 11

:$ Click2etto Extractthe ,ile$

ArcCatalogprogram$

4$ Using the=Catalog (ree> !anel at the left side of thArcCatalogapplication window Browseto yourC'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1 %ata1&aster1 ,ole

7$ ,ake Surethat the =Contents> (ab at the top of the=Catalog %ispla8>on the right side of the ArcCataloApplication Wino" is active$

Note the difference in how !rc"atalog and Windows dis#layraster datasets. !rc"atalog $%nows& that a raster dataset is

actually a collection of files ' folders, so it only shows you asingle file, where Windows ()#lorer showed all of the files.

You should always use !rc"atalog for *oving, Deleting, "o#ying, etc+ any s#atial data files, for this reason. sing !rc"ataloor these tas%s #revents critical #arts of the s#atial data files from eing $left out& and rendered useless. his is #articularly truehe case of /aster data, where multi#le raster datasets in a folder will 0share1 the 0info1 folder and their individual #ro#erties wioncatenated. While Windows ()#lorer is inca#ale of e)tracting this concatenated information 2and therefore, you cannot moo#y, delete, files without rendering them useless3, !rc"atalog 0%nows1 how to untangle the datasets from one another.






4/11

252886732.doc Page , of 11

Working with Raster Data in ArcMap

&ro'e$ting Raster Data

:6 #enthe Map %ocument &asters6m by!ou.le-Clickingon it$

;6 -n the (able of Contents Right-Clickon the ne5?:@4?;La8erand #enits !roperties$

B6 Clickon the Source (aband Scroll !ownto examine theSpatial &eference Information$

?ote that this dataset is currently using the ,eographic !oordinateSystem D/at3/onE and the ?orth American ;atum 09G7$ 'here arewo reasons we want to project this data to another

rojection3!oordinate System$ #irst the other datasets in thisroject and the project itself are using the U'M projection$ ?otsing the same projection across layers can cause problems in overlay functions Dextracting data from one layer to anotherE$

Second and as important /atitude & /ongitude are angular measurements of position relative to the center of the Carth$ 'oohat calculate surface parameters DSlope aspect etcE in Arc,-S assume that the cell si)e of a raster

ataset is measured in the same units as the elevation values$ Since the ne5?:@4?; La8eris in,!S its cell si)e is expressed in angular units rather than linear units$ Arc,-S 9$7 now ta(es care ofhis by calculating a I factor that converts the elevation units to units comparable with the units of celli)e$ 1hile this wor(s fairly well at the local level Dlarge scaleE using a single I #actor in this way willntroduce error at the small scale Dglobal levelE since degrees of /ongitude vary in linear width as youmove north and south$ #or this reason it is alwaysmore desirable to determine a projection systemppropriate for the scale region and focus of yourroject and convert your data from ,!S to thatrojection$

46 Closethe La8er !roperties %ialog6

6 #enthe Arctoolbo using theArctoolbo

#utton6

D6 Clickon the Search (abat the bottom ofthe Arctoolbo !aneland Searchon theterm 5!roect &aster6$

@6 !ou.le-Clickon the !roect &aster (oolto #enit$

6 Selectthe ne5?:@4?; La8eras theInput &aster6

?6 Browseto the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1

%ata1&aster1 ,olerand Savethe *utput &asteras 5Ele.ation6$

:36Clickon the !roperties #uttonto select the *utput CoorinateS8stem6

::6 -n the resulting dialog Clickon the Import #utton6






5/11

252886732.doc Page 5 of 11

:;6Browseto the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1 %ata1Shapefile1 ,oler and SelecttheStu85Area5pol8gon6shp file$

:B6ClickA$

:46Click*ktwice to"lythe F(M !roectionto the ne5?:@4?; La8er6

:6 'he resulting ele.ation La8erwill be added to your map document$

:D6 -n the (able *f Contents !anel !ragthe ele.ation La8erinto the Surfaces Groupand Turn #)) the 9isibilit8of thoriginal ne5?:@4?; La8er$

(ow to %lip a raster dataset toa ve$tor la)er

%aster datasets can be very large and conse*uentlyalculations based upon those datasets can be *uiterocessor intensive$ 'o minimi)e the processing timeeeded to wor( with raster data as with all dataormats it is always desirable to subset to only the area

of direct interest$

0$ Returnto theArctoolbo Search (abandSearchon the term 5clip6$

4$ !ou.le-Clickon theClip (oolfrom the %ataManagement (oolboto #enit$

7$ Selectthe !roecte 2E% Ele.ation La8erasthe Input &aster$

8$ #or the *utput Etent SelecttheStu85Area5pol8gon6shp file$

:$ !hec( the 5Use -nput #eatures for !lipping ,eometry6 Fption$


6/11

252886732.doc Page 6 of 11

7$ Selectthe ele.5clip La8er as theInput &aster6

8$ Savethe *utput &asteras slope5utm in theC'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata%ata1&aster1 ,oler$

:$ Changethe *utput Measurement to !E&CE2(5&ISE$

$ !ragthe resulting slope5utm la8er into the top of theSurfaces Group$

Using ap #lge.ra to %al$+late /ewRaster La)ers fro, # Set Of Raster0aria.les

0$ Clickon the A %ata #uttonand Browseto the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1

%ata1&aster1 ,oler$

4$ "ddthe sloperaster atasetto your Map %ocument$

7$ !ragthe slope La8erto just below the slope5pr La8erin the Surface Group$

8$ Returnto the Arc(ool#o Search (aband search on the term 5map algebra6$

:$ !ou.le-Click on the Single *utput Map Algebra (oolto #enit$

$ !rag the Surface1slope5utm la8eryou just adto theInput &aster List6

G$ Entera Space followed by the - to Su.tractfollowed by a Space$

9$ !rag the Surface1slope la8er from the Input&aster List$

0J$ !lic( on the Cnvironments 2utton andthen clic( on the ,eneral Settings -tem

expand its options$

00$se The !ro-!own To Set the Eteto 5Same as la8er slope5utm66






7/11

252886732.doc Page 7 of 11

04$Click*ktwice to run the algebraic expression you jucreated$

07$ 'he result will be added to your maps document youmay want to Turn #)) the 9isibilit8of other layers tobetter examine the results$

1hat you have created is a new raster layer that reflects thedifference between the two input raster layers$ Here thisrepresents the error introduced into the Slope calculation byrunning the Slope 'ool on a dataset that is in /at /ongcoordinates rather than a projection that has a linear unit thamatches the elevation units$

(ow to %reate a Distan$e Raster

As noted before the raster data model is used to representspatial phenomena that vary continuously through space$ 'hincludes distance$ Fne of the most useful capabilities is theability to create a raster layer that describes the distance fromgiven set of features to every point on the map$

0$

0$ Returnto the Arctoolbo Search (aband Searchon theterm 5istance6$

4$ !ou.le-Clickon theEucliean %istance (oolto #enit$

7$ Selectthe 2e"5$a.en5Air5&elease5;33;5% La8eras thInput ,eature Source %ata$

8$ 'amethe *utput %istance &aster asist;to and Save

the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%%ata1&aster1 ,oler$

:$ Setthe *utput Cell Si7e :33


8/11

252886732.doc Page 8 of 11

+ou should now have a rater dataset in which the value of every pixel reflects the Cuclidean distance Din meters the linear unithe U'M rojection SystemE to the nearest Air 'oxic %elease site$

(ow To !tra$t Raster 0al+es To 0e$tor Data?ow suppose that you would li(e to ma(e the distance value you have calculated an attribute of the schools /ayer so that youan examine the relationship between proximity and some other variable$ Here you will extract the underlying raster value fro

he dist4tox /ayer to each of the school points$ !onceptually this is similar to passing the points through the raster so that itmprints6 its attribute on the points layer$

:6 Returnto the Arctoolbo Search (aband Searchon the term 5Etract6$

;6 !ou.le-Click on the Etract 9alues (!oints (ool/ from the Spatial Anal8st(oolbo to #enit$

B6 Selectthe2e"5$a.en5Schools5"ith5S,: La8as the Input !oint ,eatures6

46 Selectthe ist;to La8eras the Inpu&aster$

6 'amethe *utput !oint ,eaturesShapefile

2e"5$a.en5Schools5"ith5S,:5ist;to and save it to the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%a%ata1Shapefile1 ,oler6

D6 Click*kto Extractthe &aster 9aluesto the school points$

@6 1hen the Etractionhas completedRight-Clickthe new

2e"5$a.en5Schools5"ith5S,:5ist;to La8er and #enitsAttribute (able$

6 Scrollto the,ar &ight and note that thedistance in meters to the nearest toxic air release site has been added aattribute$

?6 Closethe Attribute (able$






9/11

252886732.doc Page - of 11

(ow To Use The %lassi1$ation Tool To Re$lass Raster Datasetsn some cases you may want to reclassify your rasterata in order to examine how that classificationreates 5)ones$6 #or example you may want toxamine the effect of sea level rise on coastlines$

Here you will reclassify the elevclip data to reflect anncrease in se levels$

:6 Togglethe 9isibilit8of your La8ersin the(able *f Contents !aneluntil you have onlythe ele.5clip La8ervisible$

;6 Returnto the Arctoolbo Search (abandSearchon the term 5&eclass6$

B6 !ou.le-Clickon the &eclassif8 (oolfromtheSpatial Anal8st (oolbarto #enit$

46 Selectthe ele.5clip La8er as the Input&aster6

6 Clickon the Classif80 #utton6

D6 Changethe Metho %rop-%o"nto EHualInter.al so that the Classes%rop-%o"nisenabled$

@6 Changethe 2umber *f Classesto ;$

6 Under #reak 9aluesChangethe,irst 9alueto 3$

?6 Click*k$

:36:36:36:36:36:36:36:36:36'amethe *utput &astercoast+and Saveit to the

C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1 %ata1&as,oler$

::6Click*kto"lythe &eclassification$

:;6 'he new 5binar86 raster coast will be added to your(able *fContents !anel6

:B6Returnto the &eclassif8 (ool6

:46Selectthe ele.5clip La8eras the Input &aster6






10/11

252886732.doc Page 1# of 11

:6Clickon the Classif80 #utton6

:D6Changethe Metho %rop-%o"n to EHual Inter.al/so that the Classes %rop-%o"nis enabled$

:@6Changethe 2umber *f Classes to ;$

:6 Under #reak 9alues/this time Changethe,irst 9alueto :3$

:?6Click*k$

;36'amethe *utput &astercoast5:3" and Saveit to theC'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1%ata1&aster1 ,oler$

;:6Click*kto"lythe &eclassification$

;;6 'he new 5binar86 raster coast5:3 will be added to your (able *fContents !anel6

(ow to %reate Iso,etri$ %onto+rs 2ro, Rast

DataFne of the more familiar ways of depicting elevation is with the use onisometric contour lines$ 'hey are the concentric lines visible on US,S

'opographic maps that visually indicate changing elevation$ 'hese lines can li(ewise be applied to any raster data and whereppropriate can create stri(ing visualepresentations of changing values in the variable

of interest$ Here you will create contours basedpon the elevclip dataset$

:6 Togglethe 9isibilit8of your La8erssothat the ele.5clip la8eris again the onlyvisible layer$

;6 Returnto the Arctoolbo Search (ab

and Searchon the term 5Contours6$

B6 !ou.le-Clickon theContour (ool from the Spatial Anal(oolbo to #enit$

46 Selectthe ele.5clip La8eras theInput &aster$

6 'amethe *utput !ol8line ,eatures contour5m" and Sit to the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1 %ata1Shapefile1 ,oler6






11/11

252886732.doc Page 11 of 11

D6 Setthe Contour Inter.alto Dthis will create : meter contoursE$

@6 Click*kto create the contour5m La8er$

(ow to %reate (illshade I,ages

0$ Returnto theArc(oolbo Search (abandSearchon the term 5$illshae6$

4$ !ou.le-Click on the$illshae (ool from the%ata Management (oolbo to open it$

7$ Selectthe ele.5clip la8eras the Input &aster$

8$ 'amethe *utput &asterhillshae+and Saveitto the C'1temp18our5initials1 34-&aster5(he5*ther5GIS5%ata1 %ata1&aster1,oler6

:$ Setthe ,actor to ;D'his setting will 5exaggerate6 the elevation by a factor of 4 providing greater emphasis of thetopographyE$

Documents

Raster Tutorial ArcGIS 93