Understanding GIS. David SmithЧитать онлайн книгу.
started
You’ll start ArcGIS Pro, if necessary, and continue working with your project document from the last lesson.
1)Start ArcGIS Pro.
From the Catalog pane, you’ll make a copy of your Lesson1a map and name it Lesson1b. You can easily copy and paste maps in the Maps section of the Catalog pane similar to how you copy and paste files on your computer.
2)If necessary, expand the Maps item in the Catalog pane.
3)Right-click the Lesson1a map and click Copy.
4)Right-click the Maps item (the folder above Lesson1a) and click Paste.
5)Rename the copy of Lesson1a as Lesson1b.
6)Open the Lesson1b map by double-clicking the map in the Catalog pane.
Add a layer of parks
The Parkland feature class can be found in ParkSite > SourceData > ESRI.gdb > Landmark > Parkland.
1)Add the Parkland layer by dragging it to the map.
One of your geographic constraints is that the new park not be located too close to existing parks. You know from your exploration so far that there are a couple of big parks along the river, but now you can look at the whole scenario.
Symbolize the layer
A shade of green is usually the right cartographic choice for parks. ArcGIS Pro may have chosen one by a stroke of luck, but probably not. You’ll symbolize the layer after taking a look at its extent.
1)In the Contents pane, right-click the Parkland layer and click Zoom To Layer.
2)In the Contents pane, turn Parkland off and on a few times by selecting its check box. Leave it turned on.
The data extends well beyond Los Angeles, and the basemap shows that those big polygons to the north correspond to mountains. They’re probably national forests.
3)In the Contents pane, click the color patch under the Parkland layer name to open the Symbology pane.
4)Switch from the Gallery tab to the Properties tab and click the Color button to open the color palette. Click Apple Dust, a shade of green.
5)Click the Outline color button to open the color palette again.
6)Click Moss Green.
7)Click Apply in the Symbology pane.
The layer symbology is updated on the map.
Identify features
Now you can find out what attributes this layer has in the table.
1)On the Map tab, verify that the Explore tool is active by clicking on it.
2)Click on one of the big park features in the mountains to identify it.
Among the attributes are the park’s name, its type, and its acreage.
3)Leave the pop-up window open. On the Map tab, in the Navigate group, click Bookmarks > City of Los Angeles.
At this scale, you can make out the larger parks within the city.
4)Try to locate the parks mentioned earlier: the Sepulveda Dam Recreation Area, Griffith Park, and Elysian Park. Click on each one to see its attributes.
5)When you’re done, leave the Identify window open and zoom to the Dodger Stadium bookmark.
6)Identify some of the neighborhood-size parks in the view.
7)Close the pop-up window.
Your list of park requirements doesn’t have an upper size limit, but you can expect your candidates to be less than 10 acres. Your trip down the river in the previous exercise didn’t reveal any great big tracts of open land that weren’t already parks.
Label the parks layer
Some of the larger parks are already labeled in the World Boundaries and Places layer, but many of the smaller ones are not.
1)With the Parkland layer selected in the Contents pane, open the Labeling ribbon above the map and, in the Layer group, click the Label button
The parks are labeled with their names in simple black text. The information is being taken from the NAME attribute in the Parkland attribute table.
The default labels aren’t ideal for this map. The black text disappears into the imagery wherever the label doesn’t fit inside the park. In addition, the labels appear on one line, no matter how long they are.
2)On the Labeling ribbon, in the Text Symbol group, change the font to Arial (near the top).
3)Click the Color button. On the color palette, change the text color to Lemongrass.
Light-green text will show up better than black, but to be legible it still needs an outline, or halo.
4)Click the launcher button
5)On the Symbol tab, expand the Halo group.
6)Click the selector arrow next to the Halo symbol, click White fill under Polygon symbols, and click Apply (at the bottom of the pane). The default halo color is white, but you’re going to use something darker.
7)Click the Color selector under Halo, and click Moss Green.
8)Click Apply to see the result on the map.
On the map, the park labels are visible against the basemap.
Set a visibility range for the labels
The park labels look good at this fairly large scale, where there’s room to accommodate them. Now you can see what happens when you zoom out.
1)Zoom to the City of Los Angeles bookmark, located on the Map tab.
At this smaller (zoomed-out) scale, the labels overwhelm the map. You could just turn them off, of course, whenever they seem too crowded. A better solution is to make their visibility depend on the map scale.
2)With the Parkland layer selected, open the Labeling (not Appearance) ribbon.
3)In the Visibility Range group, click in the Out Beyond box and type 40000 (not 1:40,000). Then press Enter. The park labels turn off instantly because you are zoomed out beyond 1:40,000. Whenever the map scale crosses the 1:40,000 threshold, the park labels will turn off automatically.
4)Zoom to the Dodger Stadium bookmark.
As long as the map scale is larger than 1:40,000 (which means