Overriding extraction queries for chart products
The largest data source used in the creation of maritime paper chart products is the ENC. However, ENC cell boundaries rarely match the extent of a paper chart's panels 1 for 1. There may be many ENC coverages used as a source to create a single paper chart panel, or a single ENC coverage used as a source for several paper chart panels from several different charts. In the NIS workflow, this means that chart product instances often need to query the NIS for unique scale band values during extraction.
For these reasons, extraction settings for chart products in the product library are set at the instance level, and each instance represents the area of one panel from a paper chart product. This allows the Populate process in the NIS workflow to only copy certain data at the corresponding scales from the central database to the product database.
There are several things to consider when setting extraction queries for paper chart instances.
- How many panels (instances) does the chart product have?
- What data, at what scales, exists in the NIS that satisfies your area of interest so that you will not have any unwanted holes in your AOI?
- At what scale is the data shown on the paper chart vs. the scale of the source data from the NIS?
An example to illustrate chart product extraction queries is Chart 18749 produced by the United States Office of Coast Survey's Marine Chart Division.
It has two panels, each with a different scale of reference. 1902, the main panel, has a 1:20,000 scale, while the inset panel, 1903, has a 1:15,000 scale.
To obtain all the data required to create this chart, you need to know what is available in the NIS over the product's area of interest, and at what scales. Since each panel covers a different area, at potentially different scales, you will need to set different extraction queries for each instance.
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Overriding extraction queries for the main panel
Based on the available data and the extent of the AOI, the best available data for panel 1902, which has a reference scale of 1:20,000, includes data at scales of 1:12,000, 1:20,000 and 1:80,000.
In this scenario, the 1:80,000 data is unnecessary, as there is a chart element (a source diagram inset) placed over this section of the main panel's extent on the paper product that will fill this hole, so to speak.
Extraction settings for Instance 1902 should resemble those below.
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Tables |
SQL Statement |
|---|---|
|
ALL |
((IS_CONFLATE = 1 AND PLTS_COMP_SCALE >= 12000 OR ((IS_CONFLATE = 0 OR IS_CONFLATE IS NULL) AND PLTS_COMP_SCALE >= 12000 AND PLTS_COMP_SCALE <= 20000)) AND NIS_PRODUCTS <> 2 |
|
PLTS_FREL |
OBJECTID > 0 |
- If necessary, open the Product Library window.
A tree view of the product library appears.
- Navigate to the instance for which you want to override the extraction query, in this case, the instance for 1902.
- Right-click the instance and click Properties.
提示:Extraction queries can be applied at the instance level (common for nautical charts) or at the series level if all the products associated with that series will have the same compilation scale.
The properties dialog box appears for the instance.
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Click Extraction on the left side of the dialog box.
The extraction properties appear. The Settings area is blank.
- Right-click in the Settings table and click Add Record.
A new row appears in the Settings table.
- Repeat the previous step to add one more row so there is a total of two rows.
- Click the drop-down arrow in the Tables cell for the third record/row and choose PLTS_FREL as the name of the table.
The tables commonly used for Nautical extraction queries are as follows, and your two records should match these:
- ALL
- PLTS_FREL
The default option for each record you add is OVERRIDE, so you won't have to change it.
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Click the SQL Statement Browse button.
If you are using the Nautical Solution, the Please select a table to get field names from dialog box appears for the first record with the tables value of ALL.
- Choose the PLTS_COLLECTIONS table from the default list and click Select.
提示:
The default location is C:\Documents and Settings\<user login>\Application Data\ESRI\Production10.0\DMVTemplates.
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Check the Edit query text check box.
The query in the WHERE text box becomes editable.
- Paste or type the new query you want to use for the table or feature class.
Fill in the lower_scaleband_value and next_scaleband_value in the WHERE text box to reflect the correct compilation scale values for your product. These values are based on the scale band values defined for your NIS. Contact your NIS administrator for these values.
For example, if you want to extract data for the 20,000-scale panel and your NIS has data at several scale bands of 12,000, 20,000 and 80,000, your lower_scaleband_value will be 12000, and your next_scaleband_value will be 80000. Data that has a compilation scale of 80,000 will not be extracted; however, data that has a compilation scale between 12,000 and 80,000 will be extracted. See the following image as an example.
- Click OK.
The properties dialog box appears for the instance.
- Repeat steps starting at 8 for the PLTS_FREL record.
- Click OK to close the properties dialog box.
The result is a chart that has a reference scale of 1:20,000 and contains source data from 12,000 and 20,000 data.
Overriding extraction queries for the inset panel
You may also note that data at different scales is available for panel 1903. Setting the extraction queries for the inset panel are the same steps as for setting the queries for the main panel. Repeat steps 1–14 and adjust lower_scaleband and next_scaleband values in the queries for that of the inset.
For example, the data that covers the area for the inset 1903 is at 20,000. The query could be similar to ((IS_CONFLATE = 1 AND PLTS_COMP_SCALE >= 10000) OR ((IS_CONFLATE = 0 OR IS_CONFLATE IS NULL) AND PLTS_COMP_SCALE >= 10000 AND PLTS_COMP_SCALE < 30000)) AND NIS_PRODUCTS <> 2.
