May I append one ADF to another?
According to the docs:
Depending on your settings, you can learn a new area or append to an existing ADF.
Similar to the way Tango is able to learn more about an area that has been localized, I would like Tango to learn more about an area that has been localized by appending an existing ADF that is related. Tango would look for overlapping information that would relate the two files and translate the coordinates so the file being appended would use the coordinates of the main ADF.
Because there are many reasons why an area may change in appearance, you might create multiple area description files for a single physical location under different conditions and select the correct one that will be most similar to the conditions the user will have during their session. Alternatively, you could append multiple area learning sessions onto the same ADF to capture visual descriptions of the environment from every position and angle, under every variation of lighting or environmental change within one file.
The scenario would allow smaller independent "learning" sessions that could contribute to an all encompassing ADF once an application realizes the two ADF are related.
Right now, The API doesn't provide any functions for merging two or more ADFs to one. But you can append the new area's description to an existing ADF by Enable ADF : "Learning mode" and "Load ADF" mode
Check: https://developers.google.com/project-tango/overview/area-learning on "Using Learning Mode and loaded Area Description Files part"
The last one is the condition I mentioned. Also, in order to successfully append new area's description to an existing ADF, application must be localized to the existing ADF first. Then you can start learning the new area. In the end don't forget to save the new ADF, which is saved as the same uuid.
Updated: On the recent release. Append existing ADF will save as a new UUID. The new ADF area will cover your new area and the previous existing ADF.