DotSpatialTutorial3.docx

DotSpatialTutorial3.docx

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DotSpatialTutorial3

RasterDataOperationsinDotSpatial

Tutorial

（2）

Purposeofthistutorial:

BecomefamiliarwiththefollowingrasteroperationsinDotSpatial:

1.LoadingdifferentformatsofrasterdatainDotSpatial.

2.Implementingthehillshade.

3.Changethecoloroftherasterdata.

4.Multiplytherasterdata.

5.Reclassifytherasterdata.

6.Getthemouseclickedpointvaluesontherasterdatalayer.

Thistutorialhas5importantsteps.

Step1:

DownloadtheDotSpatialclasslibrary

Step2:

AddtheDotSpatialreferenceandchangethecompileoption.

Step3:

AddtheDotSpatialControlsintotheVisualStudioToolbox.

Step4:

CopytheDataExtensionsfoldertothedebugsfolderofthecurrentproject

Step5:

DesigntheGUI.（GUI-GraphicalUserInterface）

Step6:

Writethecodeforimplementingthemapoperations.

Step1:

DownloadtheDotSpatialclasslibrary

ThisstepisthesameasTutorial#1step1.

Step2:

AddtheDotSpatialreferenceandchangethecompileoption.

1.1）Addingthereferences.

DotSpatial.Data.Forms.dll,DotSpatial.Symbology.dll,DotSpatial.Controls.dll,DotSpatial.Projections.dll,DotSpatial.Data.dll,DotSpatial.Topology.dll

Fig.1Requiredreferences.

2.2）Changethecompileoption.

Changethecompileoptionfrom.NetFramework4ClientProfileto.NetFramework4.

ThisstepisthesameastheTutorial#1step2.2.

Step3:

AddtheDotSpatialControlsintotheVisualStudioToolbox.

ThisstepisthesameastheTutorial#1step3.

Step4:

CopytheDataExtensionfolderfromyourdownloadedfoldertoyourcurrentprojectbin/debugfolder.The.dllsfromthisfolderisnecessaryforGDALdataprovideraccess.

Fig.2DataExtensionsfolderfromDotSpatialdownloadedunzipfolder

Step5:

DesigntheGUI

DesigntheGUIasfollows:

Fig.3FinalGUI

Interfacedesignconsiderations.

1.Addthreepanelcontrols.Panelcontrol'spropertiesshouldbeasfollows:

Properties

Panel1

Panel2

Panel3

Name

pnlOperations

pnlLegend

pnlMap

Dock

Top

Left

Fill

2.Addfivebuttons.Buttonpropertiesshouldbeasfollows:

Properties

Button1

Button2

Button3

Button4

Button5

Name

btnLoadRaster

btnHillshade

btnChangeColor

btnMultiplyRaster

btnReclassify

Text

&LoadRaster

&Hillshade

Change&Color

&MultiplyRaster

&ReclassifyRaster

3.Addtwolabelcontrols.Labels'propertiesshouldbeasfollows:

Properties

Label1

Label2

Name

lblElevation

lblRasterValue

Text

Elevation

Row:

Column:

Value:

4.Addacheckboxanditshouldhavethefollowingproperties.

Name:

chbRasterValueText:

Rastervalueatclickedpoint

5.Addatextboxanditshouldhavethefollowingfeatures.

Name:

txtElevationText:

3000

6.Draga“Legend”controlfromtheDotSpatialtabundertoolboxanddropitonpnlLegend.Legendpropertiesshouldbeasfollows:

Name:

Legend1Dock:

Fill

7.Draga“Map”controlfromtheDotSpatialtabundertoolboxanddropitonpnlMap.Mappropertiesshouldbeasfollows:

Name:

Map1Dock:

FillLegend:

Legend1

8.Dragan"AppManager"controlfromDotSpatialtabundertoolboxanddropitontheform.

Note:

Thiscontrolisnecessaryforloadingdifferentformatsofrasterdata.

Fig.4AppManager

9.SetthepropertiesofAppManager1asfollows:

Map:

Map1Legend:

Legend1

Step:

6Loadingthedifferentformatsofrasterdata.

6.1）Importthefollowingnamespacesinthecodingwindow.

//Requirednamespaces

usingDotSpatial.Symbology;

usingDotSpatial.Controls;

usingDotSpatial.Data;

usingDotSpatial.Topology;

6.2）btnLoadRasterclickeventshouldbeasfollows:

privatevoidbtnLoadRaster_Click（objectsender,EventArgse）

{

//AddRasterLayer（）methodisusedtoloadtherasterlayersonthemap

map1.AddRasterLayer（）;

map1.ZoomToMaxExtent（）;

}

Implementingthehillshade.

btnHillshade_Clickeventshouldhavethefollowingcode.

privatevoidbtnHillshade_Click（objectsender,EventArgse）

{

if（map1.Layers.Count>0）

{

//IMapRasterLayerlayer=（IMapRasterLayer）map1.Layers[0];

IMapRasterLayerlayer=map1.Layers[0]asIMapRasterLayer;

if（layer==null）

{

MessageBox.Show（"Pleaseselectarasterlayer"）;

return;

}

layer.Symbolizer.ShadedRelief.ElevationFactor=1;

layer.Symbolizer.ShadedRelief.IsUsed=true;

layer.WriteBitmap（）;

}

else

{

MessageBox.Show（"Pleaseaddalayertothemap."）;

}

}

Changethecolor.

btnChangeColorclickeventshouldhasthefollowingevent.

privatevoidbtnChangeColor_Click（objectsender,EventArgse）

{

if（map1.Layers.Count>0）

{

//changethecolorofraster

//typecastthefirstlayertoMapRasterLayer

IMapRasterLayerlayer=map1.Layers[0]asIMapRasterLayer;

if（layer==null）

{

MessageBox.Show（"Pleaseaddarasterlayer."）;

return;

}

//setthecolorscheme

//createaninstanceforacolorscheme

ColorSchemescheme=newColorScheme（）;

//createanewcategory

ColorCategorycategory1=newColorCategory（2500,3000,Color.Red,Color.Yellow）;

category1.LegendText="Elevation2500-3000";

//addthecategorytothecolorscheme

scheme.AddCategory（category1）;

//createanothercategory

ColorCategorycategory2=newColorCategory（1000,2500,Color.Blue,Color.Green）;

category2.LegendText="Elevation1000-2500";

scheme.AddCategory（category2）;

//assignnewcolorscheme

layer.Symbolizer.Scheme=scheme;

//refreshthelayerdisplayinthemap

layer.WriteBitmap（）;

}

else

{

MessageBox.Show（"Pleaseaddalayertothemap."）;

}

}

Multiplytheraster.

btnMultiplyRastershouldhasthefollowingevent.

privatevoidbtnMultiplyRaster_Click（objectsender,EventArgse）

{

if（map1.Layers.Count>0）

{

IMapRasterLayerlayer=map1.Layers[0]asIMapRasterLayer;

if（layer==null）

{

MessageBox.Show（"Pleaseselectarasterlayer"）;

}

IRasterdemRaster=layer.DataSet;

string[]rasterOptions=newstring[1];

IRasternewRaster=Raster.CreateRaster（"multiply.bgd",null,demRaster.NumColumns,demRaster.NumRows,1,demRaster.DataType,rasterOptions）;

//Boundsspecifythecellsizeandthecoordinatesofrastercorner

newRaster.Bounds=demRaster.Bounds.Copy（）;

newRaster.NoDataValue=demRaster.NoDataValue;

newRaster.Projection=demRaster.Projection;

for（inti=0;i<=demRaster.NumRows-1;i++）

{

for（intj=0;j<=demRaster.NumColumns-1;j++）

{

if（demRaster.Value[i,j]!

=demRaster.NoDataValue）

{

newRaster.Value[i,j]=demRaster.Value[i,j]*2;

}

}

}

//savethenewrastertothefile

newRaster.Save（）;

//addthenewrastertothemap

map1.Layers.Add（newRaster）;

}

else

{

MessageBox.Show（"Pleaseaddalayertothemap."）;

}

}

Reclassifytheraster.

btnReclassifyshouldhasthefollowingevent.

privatevoidbtnReclassify_Click（objectsender,EventArgse）

{

//typecasttheselectedlayertoIMapRasterLayer

IMapRasterLayerlayer=map1.Layers.SelectedLayerasIMapRasterLayer;

if（layer==null）

{

MessageBox.Show（"Pleaseselectarasterlayer."）;

}

else

{

//gettherasterdataset

IRasterdemRaster=layer.DataSet;

//createanewemptyrasterwithsamedimensionasoriginalraster

string[]rasterOptions=newstring[1];

IRasternewRaster=Raster.CreateRaster（"reclassify.bgd",null,demRaster.NumColumns,demRaster.NumRows,1,demRaster.DataType,rasterOptions）;

newRaster.Bounds=demRaster.Bounds.Copy（）;

newRaster.NoDataValue=demRaster.NoDataValue;

newRaster.Projection=demRaster.Projection;

//reclassifyraster.

//values>=specifiedvaluewillhavenewvalue1

//values

doubleoldValue=0;

//getthespecifiedvaluefromthetextbox

doublespecifiedValue=Convert.ToDouble（txtElevation.Text）;

for（inti=0;i<=demRaster.NumRows-1;i++）

{

for（intj=0;j<=demRaster.NumColumns-1;j++）

{

//getthevalueoforiginalraster

oldValue=demRaster.Value[i,j];

if（oldValue>=specifiedValue）

{

newRaster.Value[i,j]=1;

}

else

{

newRaster.Value[i,j]=0;

}

}

}

newRaster.Save（）;

map1.Layers.Add（newRaster）;

}

}

Getthemouseclickedpointvaluesontherasterdatalayer.

SelectthechbRasterValue's"CheckedChanged"event.

fig.5ChbRasterValuecheckbox'scheckedchangedevent.

chbRasterValue_CheckedChangedeventshouldhasthefollowingevents.

privatevoidchbRasterValue_CheckedChanged（objectsender,EventArgse）

{

if（chbRasterValue.Checked）

{

IMapRasterLayerrasterLayer=map1.Layers.SelectedLayerasIMapRasterLayer;

if（（rasterLayer!

=null））

{

//setthemapcursortocross

map1.Cursor=Cursors.Cross;

}

else

{

//ifnorasterlayerisselected,uncheckthecheckbox

MessageBox.Show（"Pleaseselectarasterlayer."）;

chbRasterValue.Checked=false;

}

}

else

{

//changemapcursorbacktoarrow

map1.Cursor=Cursors.Arrow;

}

}

SelecttheMap1'smouseupevent.

fig.6Map1_MouseUpevent

map1_MouseUpeventshouldhavethefollowingcode.

privatevoidmap1_MouseUp（objectsender,MouseEventArgse）

{

if（chbRasterValue.Checked）

{

//getthelayerselectedinthelegend

IMapRasterLayerrasterLayer=map1.Layers.SelectedLayerasIMapRasterLayer;

if（（rasterLayer!

=null））

{

//gettherasterdataobject

IRasterraster=rasterLayer.DataSet;

//convertmousepositiontomapcoordinate

Coordinatecoord=map1.PixelToProj（e.Location）;

//convertmapcoordinatetorasterrowandcolumn

RcIndexrc=raster.Bounds.ProjToCell（coord）;

introw=rc.Row;

intcolumn=rc.Column;

//checkifclickedpointisinsideofraster

if（（column>0&column0&row

{

//gettherastervalueatrowandcolumn

doublevalue=raster.Value[row,column];

//showtherow,columnandvalueinthelabel

lblRasterValue.Text