|
|
|
## Module: transects.js
|
|
|
|
### Comprehensive Analysis of `transects.js`
|
|
|
|
|
|
|
|
#### Module Name
|
|
|
|
- **transects.js**
|
|
|
|
|
|
|
|
#### Primary Objectives
|
|
|
|
- The primary purpose of this module is to generate and manipulate transects (lines orthogonal to a given polygon) using geospatial data. It provides functionality to create these transects and expand them horizontally.
|
|
|
|
|
|
|
|
#### Critical Functions
|
|
|
|
1. **offsetMapper(extent, origin, theta)**
|
|
|
|
- Creates a function that maps offsets to transects based on the given extent, origin, and angle (theta).
|
|
|
|
|
|
|
|
2. **transectAccumulator(step, extent)**
|
|
|
|
- Accumulates transects by iterating over a list of coordinates, computing the necessary transects at each step.
|
|
|
|
|
|
|
|
3. **generateOrthogonalTransects(coordinates, step, extent)**
|
|
|
|
- Generates transects orthogonal to a specified polygon based on the provided coordinates, step size, and extent.
|
|
|
|
|
|
|
|
4. **expandHorizontally(transects, amount)**
|
|
|
|
- Expands the generated transects horizontally by a specified amount.
|
|
|
|
|
|
|
|
#### Key Variables
|
|
|
|
- **extent**: The width of the transect.
|
|
|
|
- **origin**: The starting point for computing displacements.
|
|
|
|
- **theta**: The angle used for computing the direction of the transect.
|
|
|
|
- **step**: The distance between consecutive transects.
|
|
|
|
- **coordinates**: The list of coordinates defining the polygon.
|
|
|
|
- **amount**: The amount by which to expand the transects horizontally.
|
|
|
|
|
|
|
|
#### Interdependencies
|
|
|
|
- **Earth Engine (ee)**: The module heavily relies on Google Earth Engine (GEE) for geospatial computations and data structures.
|
|
|
|
- **Geodesy Module**: Functions like `computeBearing` and `computeDisplacement` are imported from the geodesy module to perform geospatial calculations.
|
|
|
|
- **Metadata Module**: Uses `INTERNALS` from the metadata module to store additional information in the generated features.
|
|
|
|
|
|
|
|
#### Core vs. Auxiliary Operations
|
|
|
|
- **Core Operations**:
|
|
|
|
- `generateOrthogonalTransects`: Main function to generate transects.
|
|
|
|
- `transectAccumulator`: Core logic for accumulating transects.
|
|
|
|
- **Auxiliary Operations**:
|
|
|
|
- `offsetMapper`: Helper function for mapping offsets to transects.
|
|
|
|
- `expandHorizontally`: Function to expand transects horizontally.
|
|
|
|
|
|
|
|
#### Operational Sequence
|
|
|
|
1. **Initialization**: Import necessary modules and define helper functions.
|
|
|
|
2. **Transect Generation**:
|
|
|
|
- Use `generateOrthogonalTransects` to create transects based on input coordinates.
|
|
|
|
- Internally, `transectAccumulator` and `offsetMapper` are used to compute and accumulate transects.
|
|
|
|
3. **Expansion**:
|
|
|
|
- Optionally, use `expandHorizontally` to expand the generated transects.
|
|
|
|
|
|
|
|
#### Performance Aspects
|
|
|
|
- **Efficiency**: The use of Earth Engine's efficient data structures and algorithms ensures that the module can handle large geospatial datasets.
|
|
|
|
- **Scalability**: Designed to work with GEE, which is optimized for large-scale geospatial analysis.
|
|
|
|
|
|
|
|
#### Reusability
|
|
|
|
- **Modular Design**: Functions are designed to be reusable and can be easily integrated into other geospatial analysis workflows.
|
|
|
|
- **Parameterization**: Functions accept parameters like `coordinates`, `step`, and `extent`, making them adaptable to different use cases.
|
|
|
|
|
|
|
|
#### Usage
|
|
|
|
- **Geospatial Analysis**: Used in applications requiring the generation of transects for environmental monitoring, land use analysis, and other geospatial studies.
|
|
|
|
- **Integration**: Can be integrated into larger geospatial analysis pipelines within the GEE environment.
|
|
|
|
|
|
|
|
#### Assumptions
|
|
|
|
- **Coordinate System**: Assumes that the input coordinates are in a format compatible with GEE.
|
|
|
|
- **Earth Engine Availability**: Assumes that the Google Earth Engine service is available and accessible.
|
|
|
|
- **Geodesy Functions**: Assumes that `computeBearing` and `computeDisplacement` functions are correctly implemented and available.
|
|
|
|
|
|
|
|
This analysis provides a detailed overview of the `transects.js` module, highlighting its purpose, key components, and usage within geospatial analysis workflows.
|
|
|
|
## Flow Diagram [via mermaid]
|
|
|
|
```mermaid
|
|
|
|
graph TD
|
|
|
|
A[User] -->|Input Coordinates, Step, Extent| B[generateOrthogonalTransects]
|
|
|
|
B -->|Coordinates, Step, Extent| C[transectAccumulator]
|
|
|
|
C -->|Extent, Origin, Theta| D[offsetMapper]
|
|
|
|
B -->|Transects| E[expandHorizontally]
|
|
|
|
E -->|Amount| F[computeBearing]
|
|
|
|
E -->|Amount| G[computeDisplacement]
|
|
|
|
B -->|Transects| H[Output Transects]
|
|
|
|
E -->|Expanded Transects| H
|
|
|
|
```
|
|
|
|
## Module: transects.js
|
|
|
|
### Comprehensive Analysis of `transects.js`
|
|
|
|
|
|
|
|
#### Module Name
|
|
|
|
- **transects.js**
|
|
|
|
|
|
|
|
#### Primary Objectives
|
|
|
|
- The primary purpose of this module is to generate and manipulate transects (lines orthogonal to a given polygon) using geospatial data. It provides functionality to create these transects and expand them horizontally.
|
|
|
|
|
|
|
|
#### Critical Functions
|
|
|
|
1. **offsetMapper(extent, origin, theta)**
|
|
|
|
- **Role**: Creates a function that maps offsets to transects based on the given extent, origin, and angle (theta).
|
|
|
|
|
|
|
|
2. **transectAccumulator(step, extent)**
|
|
|
|
- **Role**: Accumulates transects along a path defined by a series of coordinates, using a specified step size and extent.
|
|
|
|
|
|
|
|
3. **generateOrthogonalTransects(coordinates, step, extent)**
|
|
|
|
- **Role**: Generates transects orthogonal to a specified polygon based on given coordinates, step size, and extent.
|
|
|
|
|
|
|
|
4. **expandHorizontally(transects, amount)**
|
|
|
|
- **Role**: Expands the generated transects horizontally by a specified amount.
|
|
|
|
|
|
|
|
#### Key Variables
|
|
|
|
- **extent**: Represents the extent of the transect.
|
|
|
|
- **origin**: The starting point for displacement calculations.
|
|
|
|
- **theta**: The angle used for calculating bearings and displacements.
|
|
|
|
- **step**: The step size for generating transects.
|
|
|
|
- **coordinates**: List of coordinates defining the polygon.
|
|
|
|
- **amount**: The amount by which to expand the transects horizontally.
|
|
|
|
|
|
|
|
#### Interdependencies
|
|
|
|
- **Earth Engine (ee)**: The module heavily relies on Google Earth Engine (GEE) for geospatial computations and data structures.
|
|
|
|
- **Geodesy Module**: Functions like `computeBearing` and `computeDisplacement` are imported from the geodesy module for geospatial calculations.
|
|
|
|
- **Metadata Module**: Uses `INTERNALS` from the metadata module to store additional information in features.
|
|
|
|
|
|
|
|
#### Core vs. Auxiliary Operations
|
|
|
|
- **Core Operations**:
|
|
|
|
- `generateOrthogonalTransects`: Main function for generating transects.
|
|
|
|
- `transectAccumulator`: Core logic for accumulating transects.
|
|
|
|
- **Auxiliary Operations**:
|
|
|
|
- `offsetMapper`: Helper function for mapping offsets to transects.
|
|
|
|
- `expandHorizontally`: Utility function for expanding transects.
|
|
|
|
|
|
|
|
#### Operational Sequence
|
|
|
|
1. **Initialization**: Import necessary modules and define helper functions.
|
|
|
|
2. **Transect Generation**:
|
|
|
|
- Use `generateOrthogonalTransects` to create transects based on input coordinates.
|
|
|
|
- Internally, `transectAccumulator` and `offsetMapper` are used to compute and accumulate transects.
|
|
|
|
3. **Expansion**:
|
|
|
|
- Optionally, use `expandHorizontally` to expand the generated transects.
|
|
|
|
|
|
|
|
#### Performance Aspects
|
|
|
|
- **Efficiency**: The use of Earth Engine's efficient data structures and algorithms ensures that the module can handle large geospatial datasets.
|
|
|
|
- **Scalability**: Designed to work with large-scale geospatial data, leveraging GEE's cloud-based processing capabilities.
|
|
|
|
|
|
|
|
#### Reusability
|
|
|
|
- **Modular Design**: Functions are designed to be reusable and can be easily integrated into other geospatial analysis workflows.
|
|
|
|
- **Parameterization**: Functions accept parameters like `coordinates`, `step`, and `extent`, making them adaptable to different use cases.
|
|
|
|
|
|
|
|
#### Usage
|
|
|
|
- **Geospatial Analysis**: Used in applications requiring the generation of transects for environmental monitoring, land use analysis, and other geospatial studies.
|
|
|
|
- **Integration**: Can be integrated into larger geospatial data processing pipelines using Google Earth Engine.
|
|
|
|
|
|
|
|
#### Assumptions
|
|
|
|
- **Coordinate System**: Assumes input coordinates are in a format compatible with Earth Engine.
|
|
|
|
- **Earth Engine Availability**: Assumes that the Google Earth Engine service is available and accessible.
|
|
|
|
- **Geodesy Functions**: Assumes that `computeBearing` and `computeDisplacement` functions are correctly implemented and available.
|
|
|
|
|
|
|
|
This analysis provides a detailed overview of the `transects.js` module, highlighting its purpose, key components, and usage within geospatial data processing workflows.
|
|
|
|
## Flow Diagram [via mermaid]
|
|
|
|
```mermaid
|
|
|
|
graph TD
|
|
|
|
A[Input Coordinates, Step, Extent] -->|generateOrthogonalTransects| B[Transects]
|
|
|
|
B -->|expandHorizontally| C[Expanded Transects]
|
|
|
|
|
|
|
|
subgraph transects.js
|
|
|
|
A --> D[generateOrthogonalTransects]
|
|
|
|
D --> E[transectAccumulator]
|
|
|
|
E --> F[offsetMapper]
|
|
|
|
D --> B
|
|
|
|
B --> G[expandHorizontally]
|
|
|
|
G --> C
|
|
|
|
end
|
|
|
|
``` |
