1  [[cha:image-to-g-code]]
  2  
  3  = Image to G Code
  4  
  5  image::images/image-to-gcode.png[align="center", alt="Image to G Code"]
  6  
  7  == What is a depth map?
  8  
  9  A depth map is a greyscale image where the brightness of each pixel
 10  corresponds to the depth (or height) of the object at each point.
 11  
 12  == Integrating image-to-gcode with the AXIS user interface
 13  
 14  Add the following lines to the '[FILTER]'  section of your .ini file
 15  to make AXIS automatically invoke
 16  image-to-gcode when you open a .png, .gif, or .jpg image
 17  
 18  ----
 19  PROGRAM_EXTENSION = .png,.gif,.jpg Grayscale Depth Image
 20  png = image-to-gcode
 21  gif = image-to-gcode
 22  jpg = image-to-gcode
 23  ----
 24  
 25  The standard 'sim/axis.ini' configuration file is already configured
 26  this way.
 27  
 28  == Using image-to-gcode
 29  
 30  Start image-to-gcode either by opening an image file in AXIS, or by
 31  invoking image-to-gcode from the terminal, as follows:
 32  
 33  ----
 34  image-to-gcode torus.png > torus.ngc
 35  ----
 36  
 37  Verify all the settings in the right-hand column, then press OK to
 38  create the gcode. Depending on the image size and options chosen, this
 39  may take from a few seconds to a few minutes. If you are loading the
 40  image in AXIS, the gcode will automatically be loaded and previewed
 41  once image-to-gcode completes. In AXIS, hitting reload will show the
 42  image-to-gcode option screen again, allowing you to tweak them.
 43  
 44  == Option Reference
 45  
 46  === Units
 47  
 48  Specifies whether to use G20 (inches) or G21 (mm) in the generated
 49  g-code and as the units for each option labeled '(units)'.
 50  
 51  === Invert Image
 52  
 53  If “no”, the black pixel is the lowest point and the white pixel is
 54  the highest point. If “yes”, the black pixel is the highest point and
 55  the white pixel is the lowest point.
 56  
 57  === Normalize Image
 58  
 59  If 'yes', the darkest pixel is remapped to black, the lightest pixel
 60  is remapped to white.
 61  
 62  === Expand Image Border
 63  
 64  If 'None', the input image is used as-is, and details which are at the
 65  very edges of the image may be cut off. If 'White' or 'Black', then a
 66  border of pixels equal to the tool diameter is added on all sides, and
 67  details which are at the very edges of the images will not be cut off.
 68  
 69  === Tolerance (units)
 70  
 71  When a series of points are within 'tolerance' of being a straight
 72  line, they are output as a straight line.
 73  Increasing tolerance can lead to better contouring performance in LinuxCNC,
 74  but can also remove or blur small details in the image.
 75  
 76  === Pixel Size (units)
 77  
 78  One pixel in the input image will be this many units--usually this
 79  number is much smaller than 1.0. For instance, to mill a 2.5x2.5-inch
 80  object from a 400x400 image file, use a pixel size of .00625, because
 81  2.5 / 400 = .00625.
 82  
 83  === Plunge Feed Rate (units per minute)
 84  
 85  The feed rate for the initial plunge movement. 
 86  
 87  === Feed Rate (units per minute)
 88  
 89  The feed rate for other parts of the path. 
 90  
 91  === Spindle Speed (RPM)
 92  
 93  The spindle speed S code that should be put into the gcode file. 
 94  
 95  === Scan Pattern
 96  
 97  Possible scan patterns are:
 98  
 99   - Rows
100   - Columns
101   - Rows, then Columns
102   - Columns, then Rows
103  
104  === Scan Direction
105  
106  Possible scan directions are:
107  
108   - Positive: Start milling at a low X or Y axis value, and move towards a
109     high X or Y axis value
110   - Negative: Start milling at a high X or Y axis value, and move towards
111     a low X or Y axis value
112   - Alternating: Start on the same end of the X or Y axis travel that the
113     last move ended on. This reduces the amount of traverse movements
114   - Up Milling: Start milling at low points, moving towards high points
115   - Down Milling: Start milling at high points, moving towards low points
116  
117  === Depth (units)
118  
119  The top of material is always at 'Z=0'. The deepest cut into the
120  material is 'Z=-depth.'
121  
122  === Step Over (pixels)
123  
124  The distance between adjacent rows or columns. To find the number of
125  pixels for a given units distance, compute 'distance/pixel size' and
126  round to the nearest whole number. For example, if 'pixel size=.006'
127  and the desired step over 'distance=.015', then use a Step Over of 2 or
128  3 pixels, because '.015/.006=2.5''.'
129  
130  === Tool Diameter
131  
132  The diameter of the cutting part of the tool.
133  
134  === Safety Height
135  
136  The height to move to for traverse movements. image-to-gcode always
137  assumes the top of material is at 'Z=0'.
138  
139  === Tool Type
140  
141  The shape of the cutting part of the tool. Possible tool shapes are:
142  
143   - Ball End
144   - Flat End
145   - 45 degree “vee”
146   - 60 degree “vee”
147  
148  === Lace bounding
149  
150  This controls whether areas that are relatively flat along a row or
151  column are skipped. This option only makes sense when both rows and
152  columns are being milled. Possible bounding options are:
153  
154   - None: Rows and columns are both fully milled.
155   - Secondary: When milling in the second direction, areas that do not
156     strongly slope in that direction are skipped.
157   - Full: When milling in the first direction, areas that strongly slope
158     in the second direction are skipped. When milling in the second
159     direction, areas that do not strongly slope in that direction are
160     skipped.
161  
162  === Contact angle
163  
164  When 'Lace bounding' is not 'None', slopes greater than 'Contact angle' 
165  are considered to be 'strong' slopes, and slopes less than that angle
166  are considered to be weak slopes.
167  
168  === Roughing offset and depth per pass
169  
170  Image-to-gcode can optionally perform rouging passes. The depth of
171  successive roughing passes is given by 'Roughing depth per pass'. For
172  instance, entering 0.2 will perform the first roughing pass with a
173  depth of 0.2, the second roughing pass with a depth of 0.4, and so on
174  until the full Depth of the image is reached. No part of any roughing
175  pass will cut closer than Roughing Offset to the final part. The following
176  figure shows a tall vertical feature being milled.
177  In this image, Roughing depth per pass is 0.2 inches and roughing
178  offset is 0.1 inches.
179  
180  .Roughing passes and final pass
181  
182  image::images/i2g-roughing.png[alt="Roughing passes and final pass"]
183