How Does SDE.ST_LENGTH() Get Calculated?

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Introduction to SDE.ST_LENGTH()

The SDE.ST_LENGTH() function is a crucial component in calculating the length of geometric features in an enterprise geodatabase. In this article, we will delve into the details of how this function gets calculated, particularly in the context of an Oracle 18c database with ArcGIS 10.7.

Understanding the Basics of SDE.ST_LENGTH()

The SDE.ST_LENGTH() function is used to calculate the length of a geometric feature, such as a polyline or a polygon. This function is part of the Spatial Database Engine (SDE) and is used to perform spatial operations on geometric features stored in the database. The function takes a geometry object as input and returns the length of the feature as a numeric value.

The Role of Oracle 18c in SDE.ST_LENGTH() Calculation

Oracle 18c is a version of the Oracle database that supports the Spatial Database Engine (SDE). The SDE is a set of spatial functions and operators that are used to perform spatial operations on geometric features stored in the database. In the context of SDE.ST_LENGTH(), Oracle 18c plays a crucial role in calculating the length of geometric features.

How SDE.ST_LENGTH() Gets Calculated

The SDE.ST_LENGTH() function uses a combination of algorithms and mathematical formulas to calculate the length of a geometric feature. The specific algorithm used depends on the type of geometry being calculated. For example, the length of a polyline is calculated using the Pythagorean theorem, while the length of a polygon is calculated using the Shoelace formula.

Calculating the Length of a Polyline

The length of a polyline is calculated using the Pythagorean theorem, which states that the square of the length of the hypotenuse of a right triangle is equal to the sum of the squares of the lengths of the other two sides. In the context of a polyline, this means that the length of each segment of the polyline is calculated using the Pythagorean theorem, and the total length of the polyline is the sum of the lengths of all the segments.

Calculating the Length of a Polygon

The length of a polygon is calculated using the Shoelace formula, which is a mathematical formula that calculates the area of a polygon. The Shoelace formula is based on the idea that the area of a polygon can be calculated by summing the areas of the triangles formed by the polygon's vertices.

The Impact of True Curves on SDE.ST_LENGTH() Calculation

In the context of an Oracle 18c database with ArcGIS 10.7, the SDE.ST_LENGTH() function can handle true curves, which are curves that are defined by a set of points in 3D space. True curves are used to model complex geometric features, such as roads and rivers, that have a non-linear shape.

When calculating the length of a polyline with true curves, the SDE.ST_LENGTH() function uses a combination of algorithms and mathematical formulas to approximate the length of the curve. The specific algorithm used depends on the type of curve being calculated.

Best Practices for Using SDE.ST_LENGTH()

When using the SDE.ST_LENGTH() function to calculate the length of geometric features, there are several best practices to keep in mind:

  • **Use the correct data type Make sure that the geometry object being passed to the SDE.ST_LENGTH() function is of the correct data type. For example, if you are calculating the length of a polyline, make sure that the geometry object is a polyline.
  • Use the correct algorithm: Make sure that the algorithm being used to calculate the length of the geometry feature is the correct one. For example, if you are calculating the length of a polyline with true curves, make sure that the algorithm being used is capable of handling true curves.
  • Use the correct units: Make sure that the units being used to calculate the length of the geometry feature are the correct ones. For example, if you are calculating the length of a polyline in meters, make sure that the units being used are meters.

Conclusion

In conclusion, the SDE.ST_LENGTH() function is a powerful tool for calculating the length of geometric features in an enterprise geodatabase. By understanding how this function gets calculated, particularly in the context of an Oracle 18c database with ArcGIS 10.7, you can use this function to perform spatial operations on geometric features stored in the database. Remember to follow best practices when using the SDE.ST_LENGTH() function to ensure accurate and reliable results.

Additional Resources

Introduction

The SDE.ST_LENGTH() function is a powerful tool for calculating the length of geometric features in an enterprise geodatabase. However, like any complex function, it can be difficult to understand and use. In this article, we will answer some of the most frequently asked questions about the SDE.ST_LENGTH() function.

Q: What is the SDE.ST_LENGTH() function?

A: The SDE.ST_LENGTH() function is a spatial function that calculates the length of a geometric feature, such as a polyline or a polygon.

Q: What types of geometry can the SDE.ST_LENGTH() function calculate?

A: The SDE.ST_LENGTH() function can calculate the length of the following types of geometry:

  • Polylines
  • Polygons
  • Multipolygons
  • Geometry collections

Q: How does the SDE.ST_LENGTH() function calculate the length of a polyline?

A: The SDE.ST_LENGTH() function calculates the length of a polyline by summing the lengths of each segment of the polyline. The length of each segment is calculated using the Pythagorean theorem.

Q: How does the SDE.ST_LENGTH() function calculate the length of a polygon?

A: The SDE.ST_LENGTH() function calculates the length of a polygon by summing the lengths of each edge of the polygon. The length of each edge is calculated using the Shoelace formula.

Q: Can the SDE.ST_LENGTH() function handle true curves?

A: Yes, the SDE.ST_LENGTH() function can handle true curves. True curves are curves that are defined by a set of points in 3D space.

Q: What are the units of measurement used by the SDE.ST_LENGTH() function?

A: The units of measurement used by the SDE.ST_LENGTH() function are determined by the spatial reference system (SRS) of the geometry being calculated.

Q: Can I use the SDE.ST_LENGTH() function to calculate the length of a geometry feature in a specific unit of measurement?

A: Yes, you can use the SDE.ST_LENGTH() function to calculate the length of a geometry feature in a specific unit of measurement by specifying the unit of measurement in the SRS parameter.

Q: What are some common errors that can occur when using the SDE.ST_LENGTH() function?

A: Some common errors that can occur when using the SDE.ST_LENGTH() function include:

  • Invalid geometry: The geometry being calculated is invalid, such as a polygon with a hole that is not properly defined.
  • Missing spatial reference system: The spatial reference system of the geometry being calculated is not specified.
  • Unit of measurement mismatch: The unit of measurement used by the SDE.ST_LENGTH() function does not match the unit of measurement specified in the SRS parameter.

Q: How can I troubleshoot errors that occur when using the SDE.ST_LENGTH() function?

A: To troubleshoot errors that occur when using the SDE.ST_LENGTH() function, you can:

  • Check the geometry being calculated for invalidity.
  • Verify that the spatial reference system of the geometry being calculated is specified.
  • Check that the unit of measurement used by the SDE.ST_LENGTH() function matches the unit of measurement specified in the SRS parameter.

Q: Can I use the SDE.ST_LENGTH() function in a SQL query?

A: Yes, you can use the SDE.ST_LENGTH() function in a SQL query to calculate the length of a geometry feature.

Q: Can I use the SDE.ST_LENGTH() function in a stored procedure?

A: Yes, you can use the SDE.ST_LENGTH() function in a stored procedure to calculate the length of a geometry feature.

Q: Can I use the SDE.ST_LENGTH() function in a map service?

A: Yes, you can use the SDE.ST_LENGTH() function in a map service to calculate the length of a geometry feature.

Conclusion

In conclusion, the SDE.ST_LENGTH() function is a powerful tool for calculating the length of geometric features in an enterprise geodatabase. By understanding how this function works and how to use it, you can perform spatial operations on geometric features stored in the database. Remember to follow best practices when using the SDE.ST_LENGTH() function to ensure accurate and reliable results.

Additional Resources