I am trying to implement a ChatBot application by using UWP (Universal Windows Platform) and Direct line api.
Here what I want to achieve is 

1. UWP ChatBot client should be able to start Camera, take picture.
The Pictures taken are saved in some local folder.
2. Next, the ChatBot should be able to upload the pictures to the Bot using  

Direct Line API Upload.

Here I do not want to use FileOpenPicker control. I want to specify the file path and call Direct Line Upload API.

I was able to upload the image file from the following API Test page which is using "File Select Control".
<https://docs.botframework.com/en-us/restapi/directline3/#>

I am wondering it is even possible to upload by specifying the File Path? (Without using File Select Control)