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Sketch on Background Image Example

Pathfinder 2014

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Sketch on Background Image Example This example demonstrates how to import a file as a background image and then create the model by

sketching. The image used is the office space of Fog Creek (we use their FogBugz software to track our

bug reports) and is displayed at http://www.joelonsoftware.com/items/2009/01/15.html . From the

Pathfinder web site, download and save the image file, named 15floorplan.png.

Figure 1: Image of the office geometry

Import Background Image To select English measurements:

1. On the View menu, click Units and select EN.

We will begin by importing the background image for sketching:

1. On the View menu, uncheck Show Snap Grid. This will allow us to sketch in the 2D view without

snapping to the grid.

2. On the Model menu, click Add a Background Image.... Open the 15floorplan.png file. This will

display the Configure Background Image dialog.

3. We first define the "Anchor Point" for the image. Type the coordinates as Model X: 0.0 ft,

Model Y: 0.0 ft, and Model Z: 0.0 ft. Click the Choose Anchor Point button and click on the mark

in the lower left of the image, Figure 2.

4. We next define two points that will be used to scale the image geometry and to rotate the

image (if needed). Click the Choose Point A button and click on the cross mark in the upper left

of the image. Click the Choose Point B button and click on the cross mark in the upper right of

the image. In the Dist. A to B textbox, type 166.0 ft, Figure 3.

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Figure 2: Define the Anchor Point on the background image. Note the red anchor point.

Figure 3: Define points A and B

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Sketch the Rooms We will now sketch the rooms on top of the background image. Remember that holding the ALT key

down temporarily disables snap-to. Also, after you define any room, you can select the room and then

select any of the points that define the shape and drag the point to adjust the shape.

To sketch the rooms:

1. In the View toolbar, click Top View ( ).

2. Zoom in on the top left of the background image and, in the left toolbar, click Add a Polygonal

Room ( ). Click to define the periphery of the room. Use a right-click to draw the last line that

closes the polygon, Figure 4. How precise you want to be when defining the room boundaries

depends on your goals. In general, the results of the evacuation analysis are relatively

insensitive to exact precision of the room dimensions.

3. With the created room selected, type 75% in the Opacity box. This will make the room 75% solid

(25% transparent) so that the underlying background image can still be seen.

4. Repeat for the adjacent office, Figure 5.

5. We will now make copies of the second office. Select the second office, then, in the tools

toolbar, click the Copy/Move Objects ( ) tool. Select Copy Mode. In the Copies box, type 10.

To define how far to move each copy, click on the lower right corner of the polygon that

describes the office and then click on the corresponding point in the adjacent office, Figure 6.

The second click will make the copies, Figure 7.

6. You will probably need to zoom in and adjust the exact positions of the offices. Select Normal

Mode to move an office without making a copy. When completed, the model will look like,

Figure 8.

Figure 4: Sketch of first office

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Figure 5: Sketch of second office

Figure 6: Preparing to copy second office

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Figure 7: After making copies of the second office

Figure 8: The copied offices

1. Continue to sketch the rooms. Figure 9 shows sketches made that go around furniture. As a

second sketch is made next to an existing room, the cursor will snap to the existing room

coordinates. Hold the CTRL key and select both rooms, then right-click and select Merge.

Continue this process to complete the sketch.

2. You can cut holes in an existing room by drawing a new polygonal room on the existing room

and deleting the polygon.

3. Continue the sketching process until you have made all the rooms for the office. Note that we

can leave the walls with a finite thickness separating the rooms. After some time, your model

will look like Figure 10.

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Figure 9: Sketching around furniture and then merging separate sketches to make one room

Figure 10: After all rooms have been defined. Note that some offices are separated by doors, so those rooms are not yet connected to the main walking space.

Add Doors Doors are added to connect all offices to the open walking space.

1. In the View toolbar, click Top View ( ).

2. Double-click the Add a new Door tool ( ).By default the doors are 32 inches wide. The Max

Depth is the maximum thickness the tool will use to search for adjoining space. Depending on

how accurately your model is sketched, you might need to increase the value.

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3. Zoom in to the upper left of the model and move the mouse to the location for the door and the

tool will snap to the adjoining spaces, Figure 11.

4. Continue adding doors until the model looks like Figure 12.

Figure 11: Adding a door to the model

Figure 12: After all doors have been added

Add Occupants We will add 80 occupants, 50 placed in offices and open space and 20 and 10 placed in the two

conference rooms.

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1. Double-click the Add an Occupant ( ) tool. Click to position 50 occupants in offices or open

space, Figure 13.

2. To add occupants to the conference room, right-click on the left conference room and in the

context menu, click Add Occupants....

3. For Placement, select Random. In the By Number box, type 20. Click OK to close the dialog and

add the occupants, Figure 14.

4. Repeat to add 10 occupants to the adjacent conference room.

Figure 13: Adding individual occupants to the model

Figure 14: Adding occupants by room

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Run Simulation To run the simulation:

1. On the File menu, select Save.

2. Save the model to a new folder on your computer and name the file fog_creek.pth.

3. On the toolbar, click Run Simulation ( ).

View Results When the simulation is finished, the 3D Pathfinder results window will display.

To view results:

1. Click the Play button.

2. At any time click the Pause or Stop button. You can drag the time line to control the animation.

3. To view occupants as people, click the Stop button, on the Agents menu, click Show as People,

then click the Play button, Figure 15.

Figure 15: The results during evacuation. They do dress nice at Fog Creek, don't they.