For the vast majority of launch monitor users, it is normal to see a slight variance between data indoors vs data outdoors. This is not due to the launch monitor itself being affected but instead is caused by a set of key differences between the indoor and outdoor environment:

• Golf Ball Type - The actual golf ball used is often the biggest distinguishing factor between indoors and outdoors. When outdoors, a range ball will not perform in the same way as a premium golf ball indoors due to differences in cover material and internal construction. Additionally, golf balls will "wear out" after being hit repeatedly. This will cause data from a range ball to be less consistent than a brand new premium ball. 
• Driving Range Slope - When on an outdoor range, if you notice your golf ball seemingly flying to a different distance than the launch monitor reports, it is important to factor in the slope of the driving range. Your launch monitor will always assume carry distance on a flat plane, and will not adjust for the slope of a range.  
• Wind - When outdoors, wind at the peak of your golf ball's flight will affect the real-world carry distance while leaving the launch monitor's carry distance reading unaffected.
• Psychological Effect - Swinging indoors vs outdoors likely WILL unconsciously affect the way you are swinging. This typically manifests as slower swing speeds which in turn generates slower ball speeds. From internal testing, even scratch golfers will see natural swing variances indoors vs outdoors. The amount of variance or in-variance will obviously come down to the specific golfer.

For almost every user, there is likely is a psychological factor. This does tend to be the most apparent with the driver, as it is the longest club in the bag which makes it the most unnatural to use indoors. We see this as users take the device from indoor to outdoor and are surprised to see that ball speed is different, which impacts carry and total distance.

If the launch angle in specific is a point of difference, and you want to be absolutely certain that your indoor environment is reading the launch angle correctly, please run the accelerometer calibration while the device is on your hitting mat. This can be accomplished by using the GC3's touch screen and navigating to Settings -> Diagnostics -> Sensors.