TP1 - Introduction to ArcGIS

Transcription

1 TP1 - Intrductin t ArcGIS During this practical, we will use ArcGIS (ArcMap and ArcCatalg) t create maps f predictrs that culd explain the bserved bird richness in Switzerland. ArcMap is principally used fr data mdificatin, calculatin and extractin, while ArcCatalg is principally used fr data preview and management. Exercise 1 Intrductin t ArcCatalg and ArcMap Intrductin: In this exercise, we will slwly start ArcMap and ArcCatalg and try t understand hw they wrk, create a pint shapefile f bservatins and imprt data int ArcMap. Exercise 1.1 Cnnecting a flder t ArcCatalg/ArcMap - Launch the ArcCatalg applicatin (g t: start > All prgrams > ArcGIS > ArcCatalg 10.1 ). - Nw, yu want t cnnect ArcCatalg t yur data s yu can wrk with its cntents. T d this, g t File > Cnnect T Flder and brwse t yur wrking directry (i.e..../practicals/). - Explre the cntent f yur TP1/Data flder using windws explrer and ArcCatalg, lk fr differences between these tw ways f lking at files. Questin 1: Name tw differences that yu can find between the Windws and the ArcCatalg explrers? - ArcCatalg is principally used fr data visualizatin, management and simple manipulatin. An ArcCatalg interface (called Catalg ) is nw available in the mre recent versin f ArcMap (> 10.0). Thus, yu can clse the ArcCatalg windw. - Launch the ArcMap applicatin (g t: start > All prgrams > ArcGIS > ArcMap 10.1 and explre the ArcMap windw. - Save the sessin in yur directry (g t: File > Save as ) under /practicals/birds.mxd - Cnnect t yur wrking directry. T d this, gt t the Catalg windw (n the right) > Cnnect T Flder ( ) and brwse t yur wrking directry (i.e.../practicals). Yur flder appears nw in the Catalg windw. - NB: A Hme directry was als created in the Catalg when yu saved the Birds.mxd in yur directry. Exercise 1.2 Creating a pint shapefile f bird richness - Open the Richness_bird.txt file with excel (.../practicals/tp1/data/). This file cntains infrmatin abut bird richness at different lcatins in Switzerland. Each rw indicate ne bservatin f bird richness and has the fllwing clumns: X: the X-crdinate f the bservatin lcatin (Swiss reference system CH1903 LV03).

2 Y: the Y-crdinate f the bservatin lcatin (Swiss reference system CH1903 LV03). Richness: bird richness at the XY lcatin. - Display this data in the GIS, s t visualize the lcatins f the sampling sites in a spatially explicit way. In rder t achieve this, create a shapefile ( pint shapefile ) frm the txt file s cntent. - In the Catalg windw, click n the small + next t the TP1 and Data flder t expand their cntent. - Right-click n Richness_bird.txt > Create Feature Class > Frm XY Table - Chse X as X Field, Y as Y Field and richness as Z Field. - Chse de CH1903 LV03 crdinate system (g t: Crdinate System f Input Crdinates ). - Name yur utput shapefile XYRichness_bird.shp and save it t yur /TP1/Data flder. - Brwse t yur /TP1/Data flder in the Catalg windw and cntrl that a new shapefile called XYRichness_bird.shp has been created in the flder. If nthing appears, right-click n the /TP1/Data flder > Refresh. Questin 2: Name the main difference(s) between ArcCatalg and the Catalg windw in ArcMap? Exercise 1.3 Adding data ( rasters / shapefiles ) int ArcMap - T add layers int an ArcMap prject, simply drag-and-drp the fllwing layers (i.e. shapefiles and rasters) frm the ArcMap Catalg windw int the ArcMap Table Of Cntents windw (n the left). Alternatively, yu can als add layers by ging t File > Add Data in ArcMap. Pint shapefile: XYRichness_bird.shp Plygns shapefiles: Lakes.shp and Rivers.shp Rasters: mnt25_1km, frest-edges_bl.rst and st_landsat500.tif - The layers are autmatically visible int the central windw. Yu can select/deselect and mve their hierarchy in the Table Of Cntents windw. Questin 3: Observe the different layers and explain what they represent? What type f data are they: vectr r raster? What is the reslutin (cell size in meters) f the different rasters? (Use the Measure tl). The raster reslutin is als given int the layer prperties (right-click n the raster layer > Prperties ). Questin 4: Bring the map t the 1: scale and center it ver the lac de Neuchâtel. Use the Measure tl. What is the length f the lake in km and in nautical miles? Hw many km 2 des it cver? - Then, access the XYRichness_bird.shp attribute table by right-clicking n the shapefile > Open Attribute Table. Questin 5: Hw many bird richness bservatins are there in the dataset?

3 Exercise 2 Creating shapefiles and data editing Intrductin: In this exercise, we will create a plygn shapefile f sme Switzerland lakes, mdify anther plygn shapefile f Switzerland lakes and merge them tgether. Then, this plygn shapefile will be cnverted int a line shapefile and merged with a river shapefile (line). Frm this final line shapefile, we will be able t create a raster f distance t the water (Exercise 3). Exercise 2.1 Creating a plygn shapefile f lakes - In the Catalg windw, right-click n the Data flder > New > Shapefile. - Chse plygn as Feature Type, CH1903 LV03 as crdinate system and name yur utput shapefile LakesNew.shp. - Brwse t yur /TP1/Data flder in the Catalg windw and cntrl that a new shapefile called LakesNew.shp has been created in this flder. If nthing appears, right-click n the /TP1/Data flder > Refresh. The LakesNew.shp shuld be autmatically added in the ArcMap Table Of Cntents windw (if nt, drag-and-drp it). Nw draw sme plygns in this empty shapefile. - Select the st_landsat500.tif and the LakesNew.shp layers in the Table Of Cntents windw. - Add the Editr tlbx: Custmize > Tlbars and select Editr. - Start an editing sessin in the Editr tlbx: Editr > Start Editing. Then, Editr > Editing Windw > Create Features. A Create Features windw appears n the right. - Select the layer yu want t edit (i.e. LakesNew.shp) in the Create Features windw. - Select the type f plygn yu want t draw (i.e. plygns ) in the Create Features windw. - Then, draw the brder f the Bienne lake with the Straight Segment tl ( ) by clicking n the map (this manipulatin creates vertices ) alng the Landsat lake brder (scrll t zm and if necessary use the hand t mve n the map). T stp the plygn drawing, duble click. The plygn is then added in the layer and a line (crrespnding t a plygn bject) is added in the Attribute Table (right-click n the LakesNew.shp layer > Open Attribute Table ). - Then, fllw the same prcedure t draw the Mrat, Thun and Brienz lakes. - Finally, Editr > Save Edits > Editr > Stp Editing. Exercise 2.2 Mdifying a plygn shapefile f lakes Select the Lakes.shp layer in the Table Of Cntents windw and start an editing sessin in the Editr tlbx: Editr > Start Editing. Select the layer yu want t edit (i.e. Lakes.shp) in the Create Features windw. The Lakes.shp layer cntains the plygns f sme Switzerland lakes. Yu will have t crrect sme drawing mistakes n the Leman and Cnstance lakes. Yu can d it by tw ways: (1) Mving vertices f the plygn: Duble click n the Cnstance lake with the Edit Tl ( ). Crrect the plygn by mving the vertices. NB: Yu can add new vertices r delete vertices by right-clicking n the plygn brders > Insert Vertex r Delete Vertex. Then, click in the plygn t validate the edits. Editr > Save Edits.

4 (2) Creating a new plygn and merging it with anther plygn. Crrect the Leman lake by creating a new plygn and merging it with the existing Leman lake plygn. Select the type f plygn yu want t draw (i.e. plygns ) in the Create Features windw. Draw the new plygn next t the existing Leman lake plygn with the Straight Segment tl ( ) and switch t the Trace tl ( ) t fllw the existing brder f the Leman lake plygn). Duble click t stp the plygn drawing. Select the tw plygns f the Leman lake by using the Edit Tl ( ). NB: Yu can als select multiple plygns with the Select features tl ( ). Merge the new plygn t the Leman lake plygn: Editr > Merge > and select the Leman lake feature. Editr > Save Edits. Editr > Stp Editing. Exercise 2.3 Merging plygn shapefiles f lakes (ArcTlbx) In rder t merge all the lakes int the same shapefile layer, a geprcessing tl shuld be applied. NB: Take a lk at the different tls prvided by ArcGIS: pen ArcTlbx ( ). - Search fr the Merge (data management) tl in the Search windw ( ). Start it. - Drag-and-drp the Lakes.shp and the LakesNew.shp layers frm the ArcMap Table Of Cntents int the Input Datasets. Name yur utput dataset Lakes.final.shp and save it t yur /TP1/Data flder. Exercise 2.4 Cnverting plygn shapefiles int line shapefiles (ArcTlbx) Since the Merge tl can nly cmbine multiple datasets f the same data type (e.g. plygns), the plygn shapefile Lakes.final.shp shuld be cnverted int a line shapefile t merge it with Rivers.shp (line shapefile). - T d this, search fr the Plygn T Line (data management) tl in the Search windw ( ). - Drag-and-drp the Lakes.final.shp layer frm the ArcMap Table Of Cntent int the Input Features. Name yur Output Feature Class Lakes.brder.shp and save it t yur /TP1/Data flder. Drag-and-drp it frm the Catalg windw int the Table Of Cntents windw. - Then, search fr the Merge (data management) tl ( Search windw ) and start it. - Drag-and-drp the Lakes.brder.shp and the River.shp layers frm the ArcMap Table Of Cntents int the Input Datasets. Name yur utput dataset Water.shp and save it t yur /TP1/Data flder.

5 Exercise 3 Wrking with raster data (grid) Intrductin: In this exercise, we will create several rasters at a 1km reslutin (cell size f 1000m) as predictr f bird species richness. All these predictrs will be extracted n the bird s XY lcatins. Then, in TP2, TP3 etc. we will try t explain the bird richness with the help f these predictrs. Exercise 3.1 Creating a raster f distance t water and sum f edges T create a raster f distance t water at 1km reslutin, we will calculate fr each cell f a grid (raster) the distance t the clsest water surce by using ur line shapefile water.shp. - Search fr the Euclidean Distance (data management) tl in the Search windw ( ). - Drag-and-drp the Water.shp layer frm the ArcMap Table Of Cntent int the Input feature surce data. Name yur Output distance raster DistTWater and save it t yur /TP1/Data flder. Set the Output cell size t G int Envirnments > Prcessing Extent and put mnt25_1km in Snap Raster. The new raster will be snapped n the mnt25_1km grid. Then, g int Envirnments > Raster Analysis and put mnt25_1km in Mask. The calculatin will run nly n the mnt25_1km cells. Run the calculatin. Then, t create a raster f sum f edges at 1km reslutin, we will calculate fr each cell f a grid (raster) the sum f the edges present in a 1km circle by using the frest-edges_bl.rst raster. - Search fr the Fcal Statistics (Spatial Analyst) tl in the Search windw ( ). - Drag-and-drp the frest-edges_bl.rst layer frm the ArcMap Table Of Cntent int the Input raster. Name yur Output raster SumEdges and save it t yur /TP1/Data flder. Set the neighbrhd as a 1000 radius circle, Map as unit and SUM as statistics type. - G int Envirnments > Prcessing Extent and put mnt25_1km in Snap Raster. The new raster will be snapped n the mnt25_1km grid. Then, g int Envirnments > Raster Analysis and put mnt25_1km in Mask. The calculatin will run nly n the mnt25_1km cells. Run the calculatin. Questin 6: Hw culd thse predictrs relevant t explain bird species richness?

6 Exercise 3.2 Creating a raster f Slpe and Slar radiatin Finally, t create a raster f Slpe and Slar radiatin at 1km reslutin, use the mnt25_1km raster. - Search fr the Slpe (Spatial Analyst) tl in the Search windw ( ). - Drag-and-drp the mnt25_1km raster layer frm the ArcMap Table Of Cntent int the Input raster. Name yur Output raster Slpe and save it t yur /TP1/Data flder. Set the utput measurement in DEGREE. - G int Envirnments > Prcessing Extent and put mnt25_1km in Snap Raster and chse Same layer as mnt25_1km in Extent. The new raster will be created and snapped n the same extent as the mnt25_1km grid. Run the calculatin. - Search fr the Area Slar radiatin (Spatial Analyst) tl in the Search windw ( ). - Drag-and-drp the mnt25_1km raster layer frm the ArcMap Table Of Cntent int the Input raster. Name yur Output raster SlarRad and save it t yur /TP1/Data flder. Set the Time settings fr June (Day 152 t 181). - G int Envirnments > Prcessing Extent and put mnt25_1km in Snap Raster and chse Same layer as mnt25_1km in Extent. The new raster will be created and snapped n the same extent as the mnt25_1km grid. Run the calculatin. Questin 7: Can yu prpse ther envirnmental predictrs that culd influence bird species richness? Exercise 4 Other tls Exercise 4.1 Reclassify raster values - Reclass the values f the Slpe raster by using the Reclassify tl ( Search windw ): 0-10=1; 10-20=2; 20-30=3; 30-40=4. - Name yur Output raster ReclassSlpe and save it t yur /TP1/Data flder. Exercise 4.2 Create a buffer

7 - Create a buffer arund the rivers by using the Buffer tl ( Search windw ): Linear unit=500m. This creates a plygn 500m arund all river segments. - Name yur Output shapefile BufferRiver and save it t yur /TP1/Data flder. Exercise 4.3 Select by attributes Questin 8: Hw many bird richness bservatins are less than 500m distant frm the rivers? - T answer this questin, g t Selectin > Select By Lcatin and select the XYRichness_bird.shp as Target layer, the BufferRiver.shp as Surce layer and intersect the surce layer feature as Spatial selectin. Run. The XYRichness_bird.shp pints included int the 500m river buffer are selected in blue n the map. Yu can nw create a new layer with these selected pints: - Right-click n the XYRichness_bird.shp layer in the Table Of Cntents > Selectin > Create Layer Frm Selected Features. A new layer is added int the Table Of Cntents, but this layer is nly a virtual subset f the surce layer. Yu can save it as an independent layer: - Right-click n the XYRichness_bird_selectin layer in the Table Of Cntents > Data > Exprt Data and name yur utput shapefile BirdSelectin and save it t yur /TP1/Data flder.