Lesson 7-1. Tracing lines, arcs, circles and hatches
Brief
description: During
this lesson you will learn about tracing modes and commands, how to apply
tracing for editing raster images, etc.
 For detailed information on these subject see chapters Tuning tracing, Tracing Modes and Commands, How
to trace in the Tracing section of the Quick Start guide.
- Create a new AutoCAD drawing.
- Using the Open
command from the rFile menu load the Trace_1.tif document from the Lesson_7
folder.
Let's use Image_1 to try tracing of
raster lines, circles and hatches.
Before tracing you need to tune the tracing parameters.
Choose Conversion
Options from the Convert menu.
In Options tab:
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Define Max.Width.
Using the Measure Value button measure the width of the widest trace line.
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 |
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| Set this parameter value slightly greater than the measured
width (e.g. if the measured width is 1.35, increase this value to
1.5 in the Max.Width
field). |
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Set the Accuracy
slider to Low.
Set orthogonalization mode for vector lines - select the Orthogonalization checkbox,
and in the Base Angle field specify 0°
.
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In Separate tab:
Set separation of vector objects by color
and width - for example, thin raster lines are to be traced with
red vector lines with a width of - 0.5mm, and thick raster lines - with
blue vector lines with a width of - 1mm.
INFORMATION:
To implement such separation you need to know raster lines widths
- you can measure them using the above mentioned Measure button. In this example,
the width of thin lines is equal to 0.25mm, thick lines - 1.35mm.
Open the Separate
tab. In the End field you see a value of 1.5 - i.e. the maximum width of
raster lines, specified by you in the Max.Width field of the Options
field.
Divide this interval into two, for example, from 0 to 1mm, and from
1mm to 1.5mm.
To do this, enter '1' in the text field, and press the New Interval 
button. The original interval will be separated into two new intervals.
In the Width
field specify the width for the vector objects created from tracing
raster lines whose widths belong to the interval, limited by the values
in the Start
and End fields.
Specify the width for vector objects equal to 0.5 for
the first interval, and 1 for the second.
In the Color field, redefine the color of resulting vector objects: red
- for the first interval, blue - for the second.
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Open the Raster To Vector toolbar.
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To trace the hatch press the Trace Hatch 
button, and then cross all hatch lines by fence. |
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It is better to trace the two large circles using the Forced circle
trace method - press the Trace Circle 
button, and then specify two opposite points on the first circle
and then do the same for the second circle. |
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button.
button, and then specify with the cursor the centerlines one
by one.
button.
