Survey point and coordinate analysis
Release 9.1 Last modified April 26, 2005	Print all topics in : "Analyzing and editing survey data"

About survey point and coordinate analysis

A survey point and its contained coordinates represent a single physical location. The point analysis tools and commands are used to authenticate the relationship between survey points, coordinates, and the physical locations they represent.

The analysis requires searching for inconsistencies in these relationships. These inconsistencies fall into two categories:

• A single physical location is represented by more than one survey point in the survey dataset.
• Survey points in the survey dataset have wayward coordinates—these coordinates fall outside a theoretical tolerance circle that represents the coordinate spread for each point.

The Survey Analyst toolbar has commands that allow you to find instances of these discrepancies and tools that facilitate the repair of these problems.

For the first category described above, a command is available that allows the discovery of survey points that lie close together. This command uses the GIS coordinates of the survey points to search for point clusters based on a tolerance that you specify. From the results, you can elect to merge survey points that represent the same physical location.

For the second category, a command is used to search for survey points that contain one or more coordinates that lie beyond a given distance from a specific location. The criteria for searching for such survey points include a distance limit for the expected spread of coordinates, and a choice for whether the search is project-based (uses the current coordinate as the center) or survey dataset-based (uses the GIS coordinate as the center).

Merging survey points

Once you discover two or more survey points in the survey dataset that represent the same physical location, it is likely that you will want to merge them.

When merging two survey points, coordinates from the source point are added to the target point, then the source point is deleted. The new current coordinate is the mean of all coordinates used to define the current coordinates for both survey points. If all the coordinates have quality information, a weighted mean is used for the new current coordinate.

If any of these coordinates do not have quality information, then the arithmetic mean is used for the new coordinate.

Survey Point Merge tool

To merge the coordinates of two survey points, you can use the Survey Point Merge tool. To use this tool, first choose a source point and then a target point on the map.

Coordinates from the source point are added to the target point, then the source point is deleted.

The new current coordinate is the mean of all coordinates used to define the current coordinates for both survey points. If all these coordinates have quality information, a weighted mean is used for the new current coordinate.

If any of these coordinates do not have quality information, then the arithmetic mean is used for the new coordinate.

Point in Tolerance command

To find clusters of survey points that fall within a specific distance tolerance of each other, use the Point In Tolerance command.

To use the command, you must specify a horizontal search tolerance and, optionally, a vertical search tolerance. The command uses the GIS coordinate of each survey point to find these clusters.

You must also specify the set of survey points in which the command should look for clusters. The choices for this set include:

• Survey points selected in the Survey Explorer
• All points in the survey dataset of the active network
• Survey points displayed in the map extents
• Survey points in the active network

After running the command, a window presents a set of locations for all places where survey point clusters are found.

You can then use the Point Merge tool to solve the conflicts that you recognize as data inconsistencies (this tool is automatically activated after the command is run). Once a pair of points has been merged, you can remove the conflict from the set by clicking the Solved button.

For more information about setting the properties of conflicts windows, see Linking survey points to feature geometry.

Coordinate out of Tolerance command

To find survey points for which coordinates are outside a defined tolerance limit, use the Coordinate out of Tolerance command. To use the command, you must specify a tolerance circle that defines the maximum acceptable spread for the coordinates.

This limit can be defined vertically, horizontally, or in both directions at once. The command can be applied using one of the following two methods:

• Local check—searches within each survey project
• Global check—searches within the whole survey dataset

You must also specify the set of survey points within which the command should perform the search. The choices for this set of survey points include:

• Points selected in the Survey Explorer
• Points within the active network
• Points within the survey dataset of the active network
• Points in the map extents

The local check method

According to the local check method, a point has coordinates that are out of tolerance if both the following criteria are true:

• The current coordinate is the mean coordinate of the survey point.
• Any coordinate used to define the mean coordinate falls outside the tolerance circle limits. The center of the tolerance circle is the current coordinate. This method will only return conflicts found in the set of coordinates defined by the project that owns a survey point.

Depending on the cause of the conflicts, the following methods can be used to solve them:

• Exclude the coordinate from defining the mean (if the mean coordinate is used as the current coordinate)
• Delete the coordinate
• Correct the coordinate by editing it (only possible if it's an imported coordinate)
• Correct a mistake in measurements of the defining computation

Survey points that are outside your defined tolerance limits are listed in the Coordinate out of Tolerance dialog box. All coordinates for these points are listed, regardless of whether or not they were used for the current coordinate.

The first row listed is the current coordinate used for the local check. Different fields are displayed in the list, and these fields depend on your choice of horizontal and vertical options.

The fields displayed are:

If a vertical check is not defined, then Elevation and Delta Height are not shown. Similarly, if no horizontal check is defined, then Easting, Northing, Delta Easting, and Delta Northing are not shown.

The global check method

Using this method, a survey point is out of tolerance if any of the current coordinates used to define its GIS coordinate fall outside the tolerance circle. Coordinates that are used for the mean are also tested against the tolerance limit. Different fields are displayed in the list, and these fields depend on your choice of horizontal and vertical options.

The columns displayed are:

• UseforGIS
• Delta Easting
• Delta Northing
• Delta Height
• Survey
• Easting
• Northing
• Elevation

If a vertical check is not defined, then Elevation and Delta Height are not shown. Similarly, if no horizontal check is defined, then Easting, Northing, Delta Easting and Delta Northing are not shown.

Clicking the Solved button removes the displayed conflict. The Coordinate out of Tolerance dialog box is not automatically updated when values are changed in the Survey Explorer. You can update the dialog box view by clicking the Refresh button.

Conflicts in coordinates derived by computation can be solved in the details view of the relevant computation. Conflicts in imported coordinates are fixed by editing the relevant coordinates in the survey point's detail page.

You can navigate to the computations or points from the Coordinate out of Tolerance dialog box. The resulting detail pages are displayed in the Survey Explorer.

Updating survey points

Like computations, survey points can have different states. They can be incomplete, incorrect, or valid.

In the multiuser environment where your survey dataset is part of an enterprise geodatabase, survey points can also be out-of-date.

Consider two projects called A and B. Both projects define coordinates for the same survey point, called P1. P1 is owned by project A.

As the owner of P1, project A has exclusive control over the GIS coordinate for P1. (It is only possible to change which projects contribute to the GIS coordinate through the survey project that owns the survey point.)

P1 becomes out-of-date when the following conditions occur concurrently:

• The current coordinate from project B is used to define the GIS coordinate for P1
• The current coordinate from project B changes

In order to detect and update all cases where the GIS coordinate of survey points is out-of-date, Survey Analyst provides a command called Update Survey Points. Using the Update Survey Points command, you can display the set of out-of-date survey points in the Point out of Date dialog box.

If the project you are editing owns the point, and you have a lock on the project, you can update the point. When you do not have a lock on a project, you will not be able to update the points that belong to that project. However, the command still provides the option to list these survey points in a read-only mode.

The Point out of Date dialog box has Previous Page and Next Page buttons that let you view all of the points individually. In this dialog box, you can choose to view the detail pages of the out-of-date survey points (these appear in the Survey Explorer). You can also update specific points or all the points in the set at once.

How to perform survey point and coordinate analysis

Using the Survey Point Merge tool

1. Start ArcMap, add the Editor toolbar, and add the Survey Analyst toolbar.
2. Add the survey projects and feature layers that you want to edit to the map.
3. Click the Editor menu on the Editor toolbar and click Start Editing.
4. Click the Survey Point Merge tool .
5. Snap to and click the Source survey point.
6. Snap to and click the Target survey point.

Using the Point in tolerance command

1. Click the Survey Analyst menu in the Survey Analyst toolbar and click Point In Tolerance.
2. Type a horizontal search tolerance value.
3. Check Vertical tolerance limit for search and type a vertical search tolerance value, if you also want to define a height range tolerance.
4. Click the Find points dropdown arrow and click your choice for specifying the set of survey points that must be tested.
5. Click OK.

The Point in Tolerance window is displayed.


6. Use the Survey Point Merge tool to merge pairs of survey points, where required.
7. Click the Previous Page and Next Page buttons to show the different conflicts collected in the window.
8. Click the Solved button to remove conflicts from the set shown in the window.
9. Repeat steps 6 through 8 for all conflicts with which you want to work.
10. Click the Close button.

Using the current coordinate of survey points to find coordinates that are out of horizontal tolerance

1. Click the Survey Analyst menu on the Survey Analyst toolbar and click Coordinate out of Tolerance.
2. Check Horizontal Distance Limit for the search tolerance.
3. Type a value for the Horizontal Distance Limit.
4. Click Local Check.
5. Click the Find points dropdown arrow and click points from active network survey.
6. Click OK.

If survey points are found that fall outside the limits you specify, the Coordinate out of Tolerance dialog box appears. Otherwise, a message is displayed indicating that no coordinates are out of tolerance for the criteria you specified.


7. Click the Previous Page and Next Page buttons to view the details of all the points with coordinate displacements that fall outside your tolerance limits.
8. Click Close.

Navigating from the Coordinate out of Tolerance dialog box to delete an incorrect coordinate

1. Run the Coordinate out of Tolerance command.
2. Click in the table of the coordinate conflicts to select any one of them from the table.
3. Right-click in the table of coordinate conflicts and click Go To Point.

The Detail page for the survey point appears in the Survey Explorer.


4. Click the leftmost column of the incorrect coordinate to select it.
5. Right-click the leftmost column and click Delete. Only imported coordinates can be deleted.
6. Click the Refresh button in the Coordinate out of Tolerance dialog box.
7. Review the details page of the survey point to make other changes, if necessary.
8. Click Solved.
9. View other conflicts by clicking the Next Page and Previous Page buttons.
10. Repeat steps 2 through 8 to delete other coordinates from points that are out of tolerance.
11. Click Close.

Navigating from the Coordinate out of Tolerance dialog box to edit an incorrect measurement

1. Run the Coordinate out of Tolerance command.
2. In the Coordinate out of Tolerance dialog box, click the row for the coordinate of the computation to which you want to navigate.
3. Right-click in the selected row and click Go To Computation

The detail page for the computation that defines the coordinate appears in the Survey Explorer.


4. Make the necessary edits to the measurement values in the computation.
5. Click the Compute button .
6. Click the Refresh button and verify that the delta values are within the limits you specified for the Coordinate out of Tolerance command.
7. Click Solved to continue with further analysis of the remaining survey points, if necessary.
8. Click Close.

Using the GIS coordinate of points selected in the Survey Explorer to find coordinates that

1. Click the Survey Analyst menu on the Survey Analyst toolbar and click Coordinate Out of Tolerance.
2. Check Horizontal Distance Limit for the search tolerance.
3. Type a value for the Horizontal Distance Limit.
4. Check Vertical Distance Limit for the search tolerance if you want to use a vertical limit. Type a value for the Vertical Distance Limit.
5. Click Global Check.
6. Click the Find points dropdown arrow and click points selected in the Survey Explorer.
7. Click OK.

If survey points are found that fall outside the limits you specify, the Coordinate out of Tolerance dialog box appears. Otherwise, a message is displayed indicating that no coordinates are out of tolerance for the criteria you specified.


8. Click the Previous Page and Next Page buttons to view the details of all the points with coordinate displacements that fall outside your tolerance limits.
9. Click Close.

Choosing the projects that define the GIS coordinate for a survey point

1. Add a detail page to the Survey Explorer for the survey point for which you want to choose projects.
2. Click the Coordinate Manager tab.
3. Click a project to view its list of coordinates for the point.
4. Double-click the row of the project that you want to have participate in defining the GIS coordinate.
5. Click Yes.
6. Press Enter.

Using Update Survey Points

1. Click the Survey Analyst menu on the Survey Analyst toolbar and click Update Survey Points.

The Update Survey Points dialog box is displayed, defining which points must be shown in the Point out of Date dialog box.


2. Uncheck Also list survey points that cannot be updated in this edit session due to project locks. This lets you exclude from the list those survey points that cannot be updated due to project locks.
3. Click the Find points dropdown arrow and click the option that you want to use for finding out-of-date survey points.
4. Click OK.
5. Click the Previous Page and Next Page buttons to view the survey points that are out-of-date.
6. Click the Update All button, and skip to step 9 if you do not need to analyze and update points individually.
7. Click the Update button to update the GIS coordinate for the displayed survey point.
8. Repeat steps 5 through 7 for all survey points that need to be updated.
9. Click the Close button.

Viewing survey point details from the Point out of Date dialog box

1. Display the set of out-of-date survey points by using the Update Survey Points command.
2. Click the Previous Page and Next Page buttons in the Point out of Date dialog box to find the survey point for which you want to see the details.
3. Click the Details button.

The Survey Explorer displays the detail page for the out-of-date survey point.


4. Repeat steps 2 and 3 to add additional survey point detail pages to the Survey Explorer.
5. Click the Previous Page and Next Page buttons in the Survey Explorer toolbar to view the different detail pages.
6. Click the Close button on the Point out of Date dialog box.

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