Help with Heat Map / Compose / Image Map Widgets

Help with Heat Map / Compose / Image Map Widgets

Hi Folks.
It looks like the heat map widget adds values of a variable together as records are stored in your bucket. Is there a way for it to just show the latest value? Everything just ends up red otherwise. 

Ideally I'd also like to find a way that Users can modify the background and add points on the map from within the dashboard like you can with the Image Marker and Compose widgets. A crude solution I'm looking at is a heap of conditions for the pin colour in the contour widget but the heat map scale is nicer. 

Essentially I'm look to create a floor level survey contour or heat map for a house. (Contours would be great but there's nothing like it currently). 

Any help appreciated.
Thanks.
Rob

Any help appreciated.