A d3s file extension is related to the Nikon image format. Seems to be obsolete.
Software that open d3s file
D3S file extension - Nikon image format
What is d3s file? How to open d3s files?
File type specification:
The d3s file extension is associated with Nikon image file format, probably supported by some digital cameras, or scanning devices.
The d3s file stores image captured by these Nikon devices.
This d3s file type entry was marked as obsolete and no longer supported file format.
This type of file is no longer actively used and is most likely obsolete. This is typically the case for system files in old operating systems, file types from long discontinued software, or previous versions of certain file types (like documents, projects etc.) that were replaced in higher versions of their original programs.
The default software associated to open d3s file:
FastPictureViewer Professional 
Company or developer:
Axel Rietschin Software Developments
FastPictureViewer is very fast picture image viewer for Microsoft Windows. It supports variety of image formats including many digital camera RAWs, Adobe DNG, OpenEXR etc.
List of software applications associated to the .d3s file extension
Recommended software programs are sorted by OS platform (Windows, macOS, Linux, iOS, Android etc.)
and possible program actions that can be done with the file: like open d3s file, edit d3s file, convert d3s file, view d3s file, play d3s file etc. (if exist software for corresponding action in File-Extensions.org's database).
Hint:
Click on the tab below to simply browse between the application actions, to quickly get a list of recommended software, which is able to perform the specified software action, such as opening, editing or converting d3s files.
d3s file viewer - programs that view d3s file - Nikon image format
Programs supporting the exension d3s on the main platforms Windows, Mac, Linux or mobile. Click on the link to get more information about FastPictureViewer Professional for view d3s file action.
