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Blob2
is a powerful and advanced blob tool. A
blob is a continuous area with the same shading limited by a contour, and
possibly a number of internal holes.
Note : Blob2 is replaced by Blob3.
Hole area 1 = H1
Hole area 2 = H2
Blob area = A
Contour area = A+H1+H2
Based
on a set of filtering criteria, the Blob2 tool finds one or more (currently
up to 32) blobs (areas
within a contour) within the region of interest (ROI).
The following results are found:
-
General
statistics (blob count, coverage)
-
Properties
of the largest blob
-
Individual
properties for the set of qualified blobs
The
tool delivers an output (child) reference coordinate system that is the
incoming reference system translated to the center of gravity of the largest
blob found.
Setup
Reference - Reference system selection
Search Area - the tool's region of interest
- Vector - list of numbered polygons
- Content - the points of the selected polygon
- New - add polygon
- Delete - remove selected polygon
- Paste new - creates a new polygon, pastes the polygon from the
clipboard and presses apply - this is the quickes way to create many
polygons
- Highlight selection - highlights the selected polygon in the
image
- Copy - copies the selected polygon to the clipboard
- Paste - pastes the clipboard to the selected polygon - will overwrite
an existing polygon
Advanced
Emphasizing gradients - Activate Sobel-filter to work on a
differentiated image
Morphology - Erode (remove) or dilate (add) the found blob area
- Example : e2d2 - erodes two pixel before dilating 2 pixels
Area Search
- Minimum threshold - minimum accepted intensity value
- Maximum threshold - maximum accepted intensity value
 - will activate a
tool parameter browser.
Note : Minimum and maximum threshold can be linked to
a result in another tool - Very often a percentile value from the
Intensity Tool
- Smooth factor - smoothes the contour - used to correct the
result contour length
Rotation of child reference
- Rotate child reference system - tools connected to this tool
will reflect the angle of the major blob
Constraints 1
A
set of constraints can be specified, limiting the blobs that are found by
the tool (result validation). The constraints
apply to each blob, and all must be satisfied for a blob to be considered
qualified.
Contour area -
Area including any holes
Blob area -
Area excluding any holes
Number of holes -
Separate holes within a blob
Size of hole -
A minimum hole area implies that the blob must have a
hole; a maximum area does not.
Intensity - used to remove blobs with an average intensity
outside the minimum and maximum values
.png)
Constraints 2
Circularity - Minimum and maximum circularity limits to
accept a blob
Note: A smooth factor of 2 or 3 will normally lead to a better
circularity estimate
Axis ratio - Minimum and maximum limit values for
axis ratio
Axis ratio is length / width of bounding box.
Angle - Minimum and maximum limit values for angle
Length of bounding box - Minimum and maximum
length limits for bounding box
Width of bounding box - Minimum and maximum width
limits for bounding box
.png)
Results
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Number
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Number
of blobs found
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Coverage
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Total
blob area in percent of the ROI-area
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Largest area
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Largest
contour area (hole area included).
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Largest
blob area
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Largest
blob area (hole area subtracted).
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Total
blob area
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Total
area of all blobs (hole area subtracted).
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Intensity
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Average
light intensity of the blob with largest contour area
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Center
of gravity
|
Center
of gravity of largest blob
given in coordinates
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Contour
area[n]
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Contour area for blob n
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Contour
length[n]
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Contour length for blob n
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Form
factor[n]
|
Contour length/Contour area for blob n
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Blob
area[n]
|
Area (ex. holes) for blob n
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Number
of holes[n]
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Number of distinct holes inside blob n
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Intensity[n]
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Average intensity for blob n
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Center
of gravity[n]
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Center, blob n given in coordinates
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Visualisation
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All
blobs
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A
line following the contour of
each blobs
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All
centers
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A
separate mark for each blob center of gravity
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All
holes
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A
line following the contour of each hole
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Center
of gravity
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A
point defining the largest blob’s center of gravity
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Error
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A
cross is shown in the ROI center if no blobs are found
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Max
contour
|
The
contour of the blob with largest contour area
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ROI
|
Region
Of Interest for the measurement
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ROIHoles
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Excluded
areas of the Region
Of Interest due to overlapping polygons
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ExecuteCmd support (see also executeCmd)
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Command
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Parameters
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Return values
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Comments
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| Set |
Object=ROI;Value=<polygon> |
ok,None |
Sets
the first ROI polygon. See Copy/paste
ROIs for details. |
| Set |
Object=ROI;Number=<number>;
Value=<polygon> |
ok,None |
Sets
the numbered ROI polygon. See Copy/paste
ROIs for details. |
| Add |
Object=ROI;Value=<polygon> |
ok,None |
Adds
ROI polygon to the end of the list. See Copy/paste
ROIs for details. |
| Get |
Object=ROI;Number=<number> |
ok,<polygon> |
Gets
numbered polygon, as Scorpion polygon (StrArr format). |
| Get |
Object=Tuple;Number=<number> |
ok,<tuple> |
Gets
numbered polygon, as Python tuple |
| Clear |
Object=ROI;Number=<number> |
ok,None |
Clears
numbered polygon (makes empty) |
| DeleteAll |
- |
ok,None |
Deletes
all polygons |
Keyboard shortcuts - More
information
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Shortcut
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Command
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Comments
|
| Ctrl-Z |
Set
ROI |
Sets
the selected polygon to points marked in the image. If only a single
point is marked, the polygon is moved, centered around the point.
If the tool dialog is not open, the first polygon is set. |
| Ctrl-1
- Ctrl-0 |
Set
polygon 0-10 |
Sets
the numbered polygon to points marked in the image. If only a single
point is marked, the polygon is moved, centered around the point. If
a new polygon is defined this way, any missing polygons in between
are set as empty. |
| Ctrl-Shift-1
- Ctrl-Shift-0 |
Clear
polygon 0-10 |
Clears
the numbered polygon (sets empty). |
| Ctrl-Shift-A |
Add
polygon |
This
is a shortcut to the 'Add polygon' button on the "Setup/Add
polygon" page, and is only effective when that page is visible. |
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