Hi Rob,
There is no integrated, easy blend function for vector polys. Steve mentions photoreal because it can be used to create blended polys. Just because it is called photoreal doesn't mean that the bit map image produced has to be a "photo" of the GE image. Keep in mind that once it is a .bmp file (with accompanying location information) a developer can repaint the image to look like anything the developer wants it to look like. You definitely will need to be familiar with layers etc. using a paint program like Photoshop or Paint Shop Pro x5 or better. The key is that the add map function of SBX lets you grab the photo from GE (a bounded poly with a photorealistic texture) and, most importantly, the location coordinates to place the photo.
In other words, that very same GE background that you created a vector poly on, can be grabbed as a map with the location coordinates using SBX and then the resulting .bmp file can be used as a canvas to create a custom textured image that can be blended using channel masks as input to the SDK Resampler. The result could be a re-textured photo .bgl that looks just like your poly, except now the edges are blended.
It is complex, but can be learned. The key is learning to do photoreal first. And, along with photoreal comes autogen annotation since photoreal .bgls suppress all autogen. Ed Wells (Falcon409) created a good set of tutorials on how to do photoreal. They can be found at:
www.sim-outhouse.comLook under: Warbirds Library tab and then down to FSX Utilities section. Look through the entries in the FSX utilities section for SBX Tutorials...first one starts on page 2 in the FSX Utilities Section. There are 10 tutorials plus the final one.
You will have to register to be able to download.
Rod