About joining parcels to the parcel fabric
This topic applies to ArcGIS for Desktop Standard and ArcGIS for Desktop Advanced only.
When new parcels are added to the parcel fabric, they need to be joined to the parcel fabric to become part of the parcel fabric layer. A newly created parcel is not yet connected to the parcel fabric layer, even if existing fabric points were used as from- or to-points in the creation of the parcel. New parcels need to be joined to the parcel fabric to be connected to the parcel fabric. Since parcels can be created as floating geometries or floating features, this allows the data entry of parcels without the knowledge of coordinates, points of beginning, or spatial references. All that is required to enter a parcel in the parcel fabric are the recorded dimensions from the plan or record of survey.
Parcel joining is an interactive process where the parcel points of a floating parcel or group of parcels are matched with their corresponding points in the parcel fabric.
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Parcel joining |
There are two join methods to choose from on the Join Parcel dialog box when joining parcels to the fabric layer:
- Fabric points held fixed, line points moved to lines
Using this method, parcels being joined are fitted cartographically and topologically to the surrounding fabric.
- Joining points held fixed at map position
Using this method, the coordinate location of the floating parcels is held fixed and the surrounding fabric is fitted cartographically and topologically to the parcels being joined.
Fabric points held fixed
Using the Fabric points held fixed method, join parcels are fitted into the surrounding parcel fabric based on the established join lines. The join parcels are cartographically fitted to the surrounding fabric such that there are no slivers, gaps or overlaps. This method is typically used when the surrounding fabric is considered equally as or more accurate than the parcels being joined.
When using the Fabric points held fixed method the following join tools are available:
- The Reset X And Y tool
resets joining parcels to their original map location if you have dragged or moved the parcels during joining. - The Bring Joining Parcel To Map Extent tool
places join parcels in the visible map extent.
Accuracy
Because join parcels are fitted cartographically to the surrounding fabric, the join parcels may be distorted to fit the surrounding fabric depending on the data quality. When joining more accurate parcels to less accurate surrounding parcels using the Fabric points held fixed method, it is important to specify the appropriate accuracy levels on the joining parcels and the surrounding parcels. If the joining parcel's accuracy is set to a higher level than the accuracy level of the surrounding parcels, a fabric least-squares adjustment will result in the surrounding parcels adjusting around the more accurate parcel and the more accurate parcel maintaining its data integrity. Parcels with a higher accuracy level have a higher weight in a fabric least-squares adjustment and will adjust less than those parcels with a lower accuracy level and lower weight.
Note:If a line point is significantly moved to fit on a parcel line, the change in geometry may cause a least squares adjustment to fail. A least-squares adjustment will fail if the geometry of the lines being moved differs from their related attributes by an amount that is larger than adjustment tolerances.
Line points
Join parcel points that are joined as line points to existing lines are automatically moved to the existing parcel lines.
If a straight parcel line is joined to a series of existing lines that are not collinear, the straight line will be bent or flexed to the position of the existing parcel points as long as the existing parcel points have been added as line points. Straight lines are bent or flexed to their line points if they lie closer to their line points than the tolerance specified for Line-point under the Edit Environment tab of the Parcel Fabric Properties dialog box.
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Note:During a least-squares adjustment, any bent or flexed lines are straightened and line points are moved onto the straightened lines. However, if a line point is significantly offset from its straight line, you can choose to keep the straight line bent to the line point.
Joining points held fixed
Using the Joining points held fixed method, join parcels are held at a fixed position and the surrounding parcel fabric is fitted to the join parcels. This method allows you to preserve the shape of accurate parcels when joining them to less accurate surrounding parcels.
Note:As long as the appropriate accuracy categories have been specified for parcels, a least-squares adjustment will preserve the spatial integrity of more accurate parcels over less accurate parcels. A least-squares adjustment will result in less accurate parcels adjusting to more accurate parcel regardless of what occurred during the joining process. The Joining points held fixed method allows you to preserve the spatial integrity of accurate parcels during joining rather than waiting to run a least-squares adjustment to establish spatial integrity.
The Joining points held fixed method is not available if Limited cartographic points as been chosen under the Edit Environment tab on the Parcel Fabric Properties dialog box. Choosing Limited cartographic points assumes that the fabric is survey-accurate and is only adjusted by a least-squares adjustment.
The Joining points held fixed method is also useful for appending parcel data with coordinates from parcel fabric XML files. The point coordinates in the parcel fabric XML file are used to place the parcels in the map extent. If parcels are appended from a different coordinate system or spatial reference, the parcels may not be visible in the map extent when first placed in the map. The Bring Joining Parcel To Map Extent tool located on the Join Parcel dialog box can be clicked to place the parcels in the visible map extent.
The following tools on the Join Parcel dialog box are also available when using the Joining points held fixed method:
- The Reset X And Y tool can be used to reset joining parcels to their original coordinates if you have dragged or moved the parcels during joining.
- Click the Use coordinate averaging check box to calculate an average (mean) between the join parcel coordinates and corresponding fabric coordinates when the fabric is fitted to the join parcels.
Note:Coordinate averaging is not available when using the Fabric points held fixed join method.
Scale and rotation
The Scale And Rotate tool 
can be used to scale and rotate the joining parcel. Using this tool, rotation and scale values can be typed in on the Join Parcel dialog box.
You can also scale and rotate joining parcels using the mouse. The scale and rotation values on the Join Parcel dialog box update as you scale and rotate the parcels.
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When using the mouse to scale and rotate joining parcels, you can snap joining parcel vertices to existing points and lines on the map.
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Snap vertex to existing fabric point. |
Tip:You can also use the Scale tool 
to scale only the joining parcels and the Rotate tool 
to rotate only the joining parcels.
Note:Line points
Existing fabric points that are joined as line points are automatically moved to the lines of the join parcel. If points on the joining parcel are added as line points to existing straight lines, these straight lines will be bent or flexed to the position of the line points such that there are no slivers gaps or overlaps. Straight lines are bent or flexed to their line points if they lie closer to their line points than the tolerance specified for Line-point under the Edit Environment tab of the Parcel Fabric Properties dialog box.
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Note:During a least-squares adjustment, any bent or flexed lines are straightened and line points are moved onto the straightened lines. However, if a line point is significantly offset from its straight line, you can choose to keep the straight line bent to the line point.
Learn more about the least-squares adjustment
Establishing join links
Join links are established between the join parcel's points and the corresponding points in the parcel fabric. Failure to establish a join link between a join parcel point and its matching fabric point will result in duplicate points for the same location. Overlapping points compromise the topological connectivity of the parcel fabric and may result in a less than optimal solution in a fabric least-squares adjustment.
Learn more about maintaining the topological structure of the parcel fabric
Join links can be manually created or created by dragging a box around the two points you want to join. To manually create a join link, the Join A Parcel Or Group Of Parcels tool 
is used to snap to the joining parcel's point and to the corresponding point in the fabric.
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Manually create a join link. |
Join links can also be automatically created by dragging a box around the two points you want to join. The Create Join Link tool 
is used to drag a box around the points to be joined.
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Drag a box to create a join link. |
Establishing join links using the trace link tool
Instead of establishing join links individually point by point, you can use the Trace Fabric To Create Join Links tool 
located on the Join Parcel dialog box to detect join links along traced boundaries. The trace link tool will detect join links between the joining parcel line and the traced boundary line if the joining parcel line lies within the specified trace link buffer.
Note:If parts of the joining parcel's lines do not lie within the trace link buffer, join links will not be established for these lines, and furthermore, join links may be incorrectly established for those lines that do lie within the buffer. Make sure that the joining parcel is well positioned within the trace link buffer to ensure that correct join links are established.
Once links have been created, click Auto Join on the Join Parcel dialog box to detect any join links or line point join links that might have been missed. Make sure to set an appropriate join tolerance for detecting line points under Auto-join settings on the Tolerances tab on the Parcel Editor Options dialog box.
Auto-joining
After at least two join links have been established, Auto Join on the Join Parcel dialog box can be clicked to detect remaining links.
Auto Join uses the transformation parameters from the existing established join links and applies them to all other points in the parcel group to detect other possible join lines. If there is a large difference in accuracy between the parcels being joined and the surrounding fabric, you may need to establish a few more join lines for Auto Join to correctly detect remaining join links.
Auto Join will also detect line point join links. A line point join link occurs when a parcel point is joined to a parcel line.
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Line point join link |
The auto-join process uses the Auto-join settings tolerance located on the Tolerances tab on the Parcel Editor Options dialog box when detecting line points. You can edit this tolerance to suit the quality of your data. For example, a small tolerance of about 0.3 feet can be used if the quality of both the joining parcel and surrounding parcels is good. If the joining parcel is more accurate than the surrounding fabric parcels, a small tolerance will not likely detect all line point links.
Note:Specifying an auto-join settings tolerance that is too large might result in incorrectly joined line points and parcel points.
If no match is found between a joining parcel's point and a point in the parcel fabric, the point will simply be transformed using the transformation parameters from the existing join lines.
Join residuals
As each parcel point is matched with its corresponding fabric point, a set of join residuals, a scale, and a rotation are recomputed and displayed on the Join Parcel dialog box.
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Join residuals, scale, and rotation |
Join residuals are computed from a transformation between the joining parcel's points and the corresponding points in the parcel fabric. If only two points are joined, a Helmert transformation is used. If more than two points are joined, a least-squares transformation is used. Each time another point is joined, join residuals, scale, and rotation are recalculated.
Join residuals are only reported when using the Fabric points held fixed join method. Join residuals are an indication of how well the unjoined parcel fits with the surrounding parcel fabric. Large join residuals may result from a situation where the parcel being joined is more accurate than the surrounding parcel fabric. Large residuals may occur when the surrounding parcel fabric has been migrated from digitized data and the parcel being joined has been entered from the survey record. Large join residuals could also indicate an error in the dimensions of the parcel being joined.