scene capture 2d result different from material look

I’m trying to using scene capture 2d to render a global mesh distance field info. The material result looks right,while wrong the caputured result.

I guess it was because the ue4 treat the scene capture camera located at (0,0,0) point, and the DF was clamped by the “Global distance field view distance”. When I’m changing this parameter,the captured result acturally changes, but can’t get a good result without clamp.

Is there any easy way to fix this issure? or any other method to store Distance Field data to Render Target?