wms2gif

A tool to create a gif from a set of wms layers

Requirements

Python 2.7.4 or newer Node.js to use as a service

Configuration

The WMS endpoints that will be fetched are found in a configuration file in python config.py that contains the following elements:

• layerDefinitions is a map with the WMS endpoint URL as the key and an array of layerObject as the value. Each layerObject is a map with name and overlay properties. name is the layer name in the WMS endpoint and overlay is the relative path to an image that will be alpha-blended with the WMS response. View the config.py file for an example
• duration is the time in seconds between each image in the resulting gif

Running the python script

The gif generation is done by the gifGenerator.py python script. It has two working modes: an interactive mode where a bounding box is specified and a bulk mode where a GeoJSON file is processed to generate Gifs from different positions

Installing the dependencies

Just run pip install requirements and the numpy and imageio packages will be installed

Script parameters

You can run python gifGenerator.py -h to see a reduced view of this information

• --file The name of the GeoJSON file to be processed. Used in bulk mode
• --bboxParam The name of the GeoJSON feature property where the bounding box is specified. Required in bulk mode
• --idParam The name of the GeoJSON feature property where the id is specified. Used in bulk mode. If none is present, an autoincrementing id is used.
• --bbox The bounding box requested in the WMS requests to create the GIF in the xMin,yMin,xMax,yMax format. Used in interactive mode.
• --output The name (without extension) of the output file. Used in interactive mode.
• --duration The duration in seconds of the gif. Used in bulk and interactive modes. If not present, the one in the configuration is used
• --srid The SRID used by the bounding box. Used in bulk and interactive modes. If not present, EPSG:3857 is used

Bulk mode example:

Given the following GeoJSON called bboxs.json:

{
    "type": "FeatureCollection", 
    ...
    "features":[
        {
            "type": "Feature", 
            "properties": {
                "id": "0", 
                "bbox_3857": "223298.192,5076488.639,223983.217,5077308.063" 
            } 
        },
        ...
    ]
}

we can run the following command to generate a gif for each feature

python gifGenerator.py --file bboxs.json -- bboxParam bbox_3857 --idParam id

The generated gifs will be written to the generated folder.

Interactive mode example:

Running the following command

python gifGenerator.py --bbox "205000.110935124,5176119.97098418,206000.110935124,5177119.97098418"

will generate a gif with a random name in the generated folder

Running as a service

This repo includes a Node Express server implementation that listens to a request, generates a GIF from a specified bounding box and sends an email with the link to download it to the given email.

Configuration

The config.js file contains the configuration of the service.

• serverURL is the base server URL used to build the email download link
• pathMainWeb is the folder where the service is running. http://serverURL/pathMainWeb/ will be used as the service entry point.
• mailServer is the address of the mail server used to send the email to the user
• emailFrom is the email address that will be used as a sender in the email The /templates/email.html contains the email text that will be sent to the user once the GIF generation is finished. The {FILE_PATH} string will be replaced by the download URL.

Using the service

The service is listening for GET requests in the pathMainWeb folder and needs bbox and email parameters

The following request http://_serverURL_/_pathMainWeb_/?bbox=&[email protected] would generate a GIF from the given bbox and send an email with a download link to [email protected] when finishes.

Take into account that the service is using the script configuration file to generate the GIF. The python script configuration section details its content.