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Dictionary:
This is an extremely small distance insignificant for the precision of your theme. It
represents the minimum distance between Nodes. ET uses the Fuzzy Tolerance to clean the
theme and to keep the Polyline topology. If nodes are found closer to each other than the
Fuzzy Tolerance they are moved to form one node. All the features with length
smaller than this tolerance are considered redundant. The default tolerance is
0.000001 * (W + H ) / 2: where W is the width and H is the Height of the the extent
of the editing theme. If the editing theme has extents 1km/1km the default tolerance will
be 1mm. The MIN tolerance the user can set is 0.000000001* (W + H ) / 2. The MAX tolerance
can be 0.00001* (W + H ) / 2.
The smaller the value of Fuzzy Tolerance is, the bigger is the possibility of encountering
PseudoPseudo Nodes. If the value of the tolerance is
close to the MAX value some undesirable result might occur.
ARC/INFO uses Fuzzy Tolerance for many procedures - Clean, Intersect etc., but it has
not been implemented in ArcView. If you use ArcView standard split tool
to split a Polyline and then analyze the nodes (you can use ET, ET-Demo or any other
script or extension which does that) in many cases you will see picture like this:
. The definition of Pseudo node
is "Pseudo nodes occur where a single line connects with itself or where only
two Polylines intersect.". Why then we have here Pseudo nodes where four Polylines
intersect? The answer is in the next picture. If you zoom in enough you will
see something similar to this: 
Actually the four arcs do not intersect in one point. In
fact two of them do not intersect at all. The distance between the two Pseudo nodes in my
example is 4.58286*E-13. OK ArcView does not have problem
with the lack of actual intersection. If you use Network Analyst to find the best route it
will find it like this: 
.
This does not harm at all because the distance difference is almost nothing. However if
you want to perform some cleaning exercise on your data it can cost you a LOT.
This phenomenon (most probably caused by ArcView's single precision numbers and the
lack of Fuzzy Tolerance) I called PseudoPseudo Nodes and this is the term I'm using in ET.
If you are sometimes frustrated from the speed of cleaning procedure, know that half of it
is because of PseudoPseudo Nodes.
- Dangling node - normally refers
to unconnected node of a dangling Polyline
indicated in ET with a red dot.
- overshoot -
- undershoot -
- Pseudo node - Pseudo nodes occur
where a single line connects with itself or where only two Polylines intersect
indicated in ET with a blue dot.
- PseudoPseudo node - what is this animal?
- Fuzzy Tolerance
- Clean Polyline theme - a theme
with correct topology
- each intersection between two lines must be represented with a single node
- no double lines present
- no overshoots and undershoots present
- Generalization - The process of
removing the number of vertices required to represent a Polyline
- Grain Tolerance - controls the
distance between the vertices in a Polyline. Used with Generalize, Densify,Spline
- Projected Views - EditTools works with DATA(shapefiles) in any projection. It will not work
with themes in projected VIEWS. There is a big difference between projected DATA and
projected VIEW. If your VIEW is projected it projects your data on the fly from decimal
degrees (Geographic Projection) to the projection set in the View's properties. It does
not change your data, only the representation of the data on the screen. If your data is
in decimal degrees and your VIEW is projected then you just have to open your data in
different (unprojected) view and edit it there.If your DATA is projected then you can use
EditTools without any problems at all