Scatter Visual Only Shows 3500 Data Points - How to work around this?

The Scatter Visual seems to limit the number of data points it will render to 3500.

This is fine, but my issue is this: When I make a rectangular lasso selection in the Scatter, it only selects from the points that it decided to render. How can I expand the selection to include ALL the points in the selected region? 

For example, if I select a region that has 100 points, but only 30 of them are rendered in the Scatter Visual, I want the other visuals to show insights on ALL the points in that region – not just the 30 selected.

I wrote a measure along these lines just to count data points: 

Total in Region (including hidden) = CALCULATE(
   DISTINCTCOUNTNOBLANK(Table1[ID]), 
   Table1[X_img] >= MIN(Table1[X_img]) && 
   Table1[X_img] <= MAX(Table1[X_img]) && 
   Table1[Y_img] >= MIN(Table1[Y_img]) &&
   Table1[Y_img] <= MAX(Table1[Y_img])
)

It sort of works, but it's hit or miss when other selections are made, and I don't think it's the best way anyway. Ideally, I could capture the two opposite cornes of the selection rectangle and have those as parmaters I could use in other measures for filtering. Not sure. 

Can anyone help? Thanks.