| Table of Contents | ||||||
|---|---|---|---|---|---|---|
|
...
How should I cite SNAP?
If you want to cite SNAP you can use the following suggestion:
SNAP - ESA Sentinel Application Platform v{LATEST-VERSION}, http://step.esa.int
A specific Toolbox can be cited like:
S1TBX - ESA Sentinel-1 Toolbox v{LATEST-VERSION}, http://step.esa.int/
Just replace {LATEST-VERSION} with the actual version, e.g.
SNAP - ESA Sentinel Application Platform v6.0.7, http://step.esa.int
S1TBX - ESA Sentinel-1 Toolbox v7.0.1, http://step.esa.int/
...
It can happen that some messages are still printedeven if the level is set to OFF. For example by third party libraries or plugins which do not use the logging system of SNAP but use other means to print messages.
What to include in a forum post when reporting an issue?
Before you open a new topic, please use the search function of the forum to check if your problem is already discussed in existing topics. To keep the forum structure clean, please consider continuing discussions in existing topics before creating a new topic on similar issues. Once your post has been submitted, the corresponding topic will automatically be visible at the top of the topic list.
When reporting an issue, try to include as much information as possible to allow developers to reproduce the problem including:
Toolbox version and operating system, amount of RAM
Identify the relevant satellite products by giving the full name of the product
List the exact processing steps needed to recreate the issue
Attach relevant screen captures and resulting images (copy and paste function)
Attach the log file to your post. See https://senbox.atlassian.net/wiki/spaces/SNAP/pages/1898053693/SNAP+FAQs#How-to-find-the-log-files%3F
In case you processed a graph file, please upload the XML as well (using the upload button)
It also helps to understand when you shortly describe your overall aim (e.g. water change detection, vegetation monitoring...)
In case you get an error message, please include it in your question (again, please also check the search function if this error message has already been reported/solved)
If you work with multiple products, please mention if the error occurs for all of them or just for one specific product.
...
Try setting the property -Djava.net.preferIPv4Stack=true in the gpt.vmoptions file
and to the snap.conf file (without ‘-D’) in the etc folder.
What does the “dl” unit mean?
The dl means dimensionless. The variable has no unit.
https://en.wikipedia.org/wiki/Reflectance#SI_radiometry_units
How to create an RGB composite from individual bands?
When having 3 data products with the individual bands for the channels of the RGB image you want to create, you needed to reference the products in the expressions of the RGB Image creation dialogue.
Right-click on one product and select “Open RGB Image Window“. In the example image, all bands have the same name ‘band_1' and you have to reference the correct product for the channels. Each product has a reference number which you can see in the Product Explorer. To reference ‘band_1’ in product 2 use the expression '$2.band_1'.
That’s the quickest way.
...
In this line, you'll find an option like -J-Xmx5G. It defines how much of your total available RAM can be used by SNAP. By default, it is set to ~75% of the maximum value (here: 5G stands for 5 of 8 gigabytes of RAM). In case your system has more RAM, you can increase the -J-Xmx value. For 16 GB RAM, you could set the value to 12G, for 32 GB RAM to 24G and so on. For systems with more RAM, it was reported (here) that already 50% of the available RAM is a suitable setting and more effective than 75%. A second option is to increase the cache size (by default 1024) to 2048 or 4096. This can be done in the SNAP under Tools\Options in the Performance tab. This tab also allows you to find the ideal configuration of your system using a selected benchmark operator and clicking "compute". If you experience the error on the command line with gpt or pconvert you need to change different files. You need to change the corresponding vmoptions files, either gpt.vmoptions or pconvert.vmoptions (in the 'bin' folder). Change the value after -Xmx in the last line.
Note: In addition, it can help to quit applications currently not used. This can free memory being used by SNAP for the processing. Applications worth to be quit, can be monitored by monitoring tools of the operating system.
Related questions
...
Many tutorials a linked on the STEP page in the Tutorial section. More guides und how-tos can be found in the SNAP wiki.
How to maintain GPT performance as fast as possible?
...
In order to write intermediate results to disk you need to add the Write operator to the graph. For the final result a Write operator is added automatically to the graph by gpt. So, all you need is to specify the target on the command line.
How to best batch the gpt e.g. using just DOS-batch or using python
For batch processing there is an example available in our SNAP wiki.
For python there are meanwhile some examples available in this forum. Probably reading this thread (Example script for multiple operations?) will help you.
But you can also do batch processing from the Desktop application. See in the menu at Tools --> Batch Processing.
It depends on you what you like most.
Related questions
Are there recommended graphs or example graphs available?
Recommended graphs can be found in the Graphs menu of the Graph Builder.
Related questions
A process related to digital elevation models is taking forever to finish
...