This tutorial demonstrates how to drape an image on an AutoCAD Civil 3D surface object.
You can drape an existing image on a surface. However, this tutorial demonstrates how to obtain a useful image by using the Google Earth™ mapping service import/export features in AutoCAD Civil 3D.
The Drape Image command combines the following operations into a few simple steps:
■ A new render material is created from the source image, with mapping based on the scale, position, and rotation of the source image.
■ The new render material is applied to the selected surface object. Like other render materials, the effect of the draped image is visible only when viewing the image in 3D.
NOTE AutoCAD Civil 3D makes it easy to retrieve low-resolution, public image and terrain data from Google Earth. While the data you can retrieve from Google Earth may not be suitable for detailed design, it can be useful for project planning and presentation.
For more information, see the AutoCAD Civil 3D Help topics Draping Images on Surfaces and Google Earth Import and Export.
Exercise 1: Publishing Surface Data to Google Earth
In this exercise, you will publish the surface data of a drawing to Google Earth.
Then, Google Earth will use the coordinate system specified in the drawing settings to retrieve an image of the area around the surface.
The coordinate system specified in the drawing settings will be used to transform data as it is imported to or exported from Google Earth.
NOTE For best results, make sure that you have Google Earth version 4.0 or later.
For more information, see the AutoCAD Civil 3D Help topic Publishing Civil Data to Google Earth.
Publish surface data to Google Earth
1 Open Surface-8.dwg, which is located in the tutorial drawings folder (page 819).
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2 Start Google Earth.
3 Click Output tab ➤ Publish panel ➤ Publish To Google Earth . 4 In the Publish AutoCAD DWG To Google Earth wizard, on the Describe
page, you can enter information that will be used to create a new, temporary entry in the Temporary Places folder, in the Places pane in Google Earth.
Specify the following parameters:
■ Name: Aerial Mapping_NH83F
This field is automatically populated by the drawing name.
■ Description: Aerial mapping of a project in New Boston, NH
■ Hyperlink: blank 5 Click Next.
6 On the Items page, select the Selected Model Space Entities option.
This makes the button available, which you use to pick the specific objects in the drawing that you want to publish to Google Earth.
7 Click .
8 When you are prompted to select an object, pan and zoom to the upper left corner of the surface. Click the red line that defines the extents of the surface. If you pan or zoom to click the border, reset the zoom by entering ‘Z, and then P on the command line. Press Enter to accept the selection.
9 In the Publish AutoCAD DWG To Google Earth wizard, on the Items page, notice that one entity (the surface extents boundary) has been selected. Ensure that Publish Entity Information is selected.
10 Click Next.
11 On the Geo-Reference page, notice that the Drawing Coordinate System Transform option is selected. NAD83 New Hampshire State Planes, US Foot is listed as the zone. This information is taken directly from the world coordinate system setting specified in the drawing settings. Notice that if you select the User-Defined Transform option, you can manually select coordinates. Ensure that the Drawing Coordinate System Transform option is selected.
12 Click Next.
13 On the Nudge page, you can fine-tune the image location, using DWG linear units. Select the Drape Entities On Ground option.
14 Click Next.
15 On the File page, you can specify a file location for the KMZ data file that Google Earth creates. Click . Navigate to the My Civil Tutorial Data folder (page 819). Click Save.
16 Click Publish. When the Publishing Status indicates that the model has been 100% published, click View.
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Google Earth takes focus, panning and zooming to the specified coordinates and displaying the polygon that defines the extents of the surface. Notice that the name and description that you entered in the Publish AutoCAD DWG To Google Earth wizard has been used to create a new entry in the Temporary Places folder in the Google Earth Places pane. When you exit Google Earth, you are prompted to specify whether to save the new location to the My Places folder.
17 In the Google Earth window, in the Places pane, under Temporary Places, clear the Aerial Mapping_NH83F check box.
Clearing this check box turns off the polygon that defines the extents of the surface. The polygon was exported from AutoCAD Civil 3D so that you can confirm the image location. Clearing the Aerial Mapping_NH83F
check box turns the polygon off, which prevents it from being imported back into AutoCAD Civil 3D.
NOTE If Google Earth zooms past the polygon, expand the Temporary Places ➤ Aerial Mapping_NH83F ➤ Model ➤ Polyline collection. Double-click Polyline to zoom to the extents of the polyline.
To continue this tutorial, go to Exercise 2: Importing a Google Earth Image (page 121).
Exercise 2: Importing a Google Earth Image
In this exercise, you will import an aerial image from Google Earth into AutoCAD Civil 3D.
To provide a useful source image, Google Earth must display the image from directly above. If the image is tilted, it will still be captured by AutoCAD Civil 3D. However, it will not be a useful representation of the surface when it is converted to a render material.
When the Google Earth image is imported into AutoCAD Civil 3D, it appears in the drawing as a gray scale image object. The image is scaled by both the linear units in the drawing and the extents of the latitude/longitude of the image. The image aspect ratio matches that of the image displayed in the Google Earth window. AutoCAD Civil 3D automatically generates a name for the image, using the first three letters of the drawing file name and a unique ID number. The image is saved in the same directory as the drawing file.
When the image is draped on the surface, a new render material is created from the image, and the render material is applied to the surface. If the image is larger than the surface, the image is clipped to the extents of the surface object. If multiple, smaller images are needed to cover a surface, you must combine them into a single image.
TIP If you do not want to get your surface image from Google Earth, you can use Autodesk Raster Design to prepare images from other sources. Using Raster Design, you can
■ combine multiple images into a single image.
■ convert images to a format (such as BMP, DIB, GIF, JPG, PCX, PNG, RLE, TGA, or TIF) that is suitable for use as a render material.
■ orient and scale an image appropriately for a drawing.
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For more information, see the AutoCAD Civil 3D Help topic Importing a Google Earth Image to AutoCAD Civil 3D.
This exercise continues from Exercise 1: Publishing Surface Data to Google Earth (page 117).
Import a Google Earth image
NOTE This exercise uses Surface-8.dwg with the modifications you made in the previous exercise.
1 In Google Earth, ensure that the image is viewed from directly above.
If the Google Earth navigation controls are not visible, hover the cursor over the compass at the upper right-hand corner of the screen:
Compass
Navigation Controls
■ To reset the tilt so that the image is viewed from directly above, double-click . Alternatively, you can press the R key to reset the tilt.
■ To reorient the view so that North is oriented toward the top of the screen, click . Alternatively, you can press the N key to reset the North orientation.
■ To pan back to the view that was originally published, double-click the appropriate link under Temporary Places.
2 Click Insert tab ➤ Import panel ➤ Google Earth drop-down ➤ Google Earth Image .
3 When prompted to select a coordinate system for image location, press Enter to accept the default Coordinate System selection.
The gray scale Google Earth image appears in the drawing window in the appropriate location under the surface object. The image was placed on the current layer, which is named Image in the current drawing.
To continue this tutorial, go to Exercise 3: Draping an Image on a Surface (page 124).
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Exercise 3: Draping an Image on a Surface
In this exercise, you will drape an image onto a surface, creating a render material from the image.
First, you will review a surface style to learn about some common settings that provide an acceptable view of the draped image on the surface. When you drape an image on a surface, the image is applied to the surface as a render material. However, it is not evident that you have applied a render material when you view the surface in plan view. The surface style must be set up to view the surface in model.
For more information, see the AutoCAD Civil 3D Help topic Draping Images On Surfaces.
This exercise continues from Exercise 2: Importing a Google Earth Image (page 121).
Examine the surface style
NOTE This exercise uses Surface-8.dwg with the modifications you made in the previous exercise.
1 In Toolspace, on the Prospector tab, under the drawing name, expand the Surfaces collection. Right-click Aerial Mapping. Click Edit Surface Style.
In the Surface Style dialog box, on the Display tab, examine the current surface style, 5’ Contours. Notice that the style displays the surface border and major and minor contours when the surface is viewed in plan view.
2 From the View Direction list, select Model.
Notice that the surface style is set to display only triangles when the surface is viewed in model view.
3 Click the Triangles tab.
Notice that the Triangle Display Mode is set to Exaggerate Elevation and the Exaggerate Triangles By Scale Factor is set to 3.000.
These settings specify that when the surface is displayed in model view, the triangle elevations are exaggerated by a factor of three. The
exaggeration makes the variations of the surface more obvious than if the surface was not exaggerated.
4 Click Cancel.
Drape the image on the surface
1 Click Surface tab ➤ Surface Tools panel ➤ Drape Image .
2 In the Drape Image dialog box, select the following information from the Image and Surface lists. All the images and surfaces available in the current drawing appear in the lists. Alternatively, you can click to pick the image or surface directly in the drawing window.
■ Image: SurXXX
■ Surface: Aerial Mapping
NOTE The image name is automatically generated when it is imported into AutoCAD Civil 3D. Your image name and render material name may differ from the names that are shown in this tutorial.
The Render Material Name field is populated with an automatically generated name (Aerial Mapping_SurXXX_RenderMaterial). You can change this name as desired, but accept the default for this exercise.
3 Click OK.
The image is draped on the surface, but it is not evident in plan view.
Next, you will hide the image, and then view the surface in model view.
4 In the drawing window, select the image. Right-click. Click Isolate Objects ➤ Hide Selected Objects.
NOTE To make the image reappear, right-click in the drawing area and click Isolate Objects ➤ End Object Isolation.
5 Click View tab ➤ Views panel ➤ views list ➤ SE Isometric.
This selection specifies an appropriate angle at which to view the surface in 3D.
6 On the command line, enter Zoom. When prompted, enter O to select an object.
7 When prompted to select an object, in the drawing window, click the surface. Press Enter to accept the selection.
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8 Click View tab ➤ Views panel Visual Styles drop-down ➤ Realistic.
The gray scale Google Earth image appears draped over the surface. Notice that because the image was larger than the surface, the image has been clipped to the extents of the surface.
9 On the command line, enter Materials.
10 On the Materials palette, notice that a new render material has been created and is using the imported image as a diffuse map. The render material name and image name correspond to the names that you specified.