As per document Asset Selector ,   http://localhost:4502/aem/assetpicker.html?dialog=true  Use these parameters to open the asset selector as Granite Dialog. This option is only applicable when you launch the asset selector through Granite Path Field, and configure it as pickerSrc URL.

I tried the following code in the dialog XML:

<image
   jcr:primaryType="nt:unstructured"
   sling:resourceType="granite/ui/components/coral/foundation/form/pathfield"
   name="./videoThumbnail"
   pickerSrc="/aem/assetpicker.html?dialog=true"

   mimeType="image"
   rootPath="/content/dam"/>

The pathfield above does not seems to use the alternative picker specified by the pickerSrcand behaves like a standard pathfield.

Also tried adding the extra URL parameters as specified in the pathfield docs but that made no change.

Please provide ur inputs how to configure assetpicker in dialog.

Regards,

Kalyan.