Invisible section plan

Need help with 3D modeling. Fairly new to SU but been learning a lot on the go. I am modeling a House with a large Deck, which will hold an enclosure. As I am rotating the image part of the model disappears like the there is a section plane. I have not put any sectional planes in. I have drawn this with SU 18 and 19 and i am getting the same thing.

Looks like your in “parallel projection” mode. Go to “Camera” and check “perspective”.

What is the Difference? For knowledge.

In Parallel Projection mode it is easy to inadvertently move the invisible picture plane so that it cuts your model. In perspective it only happens when the model extents are very large and you want to zoom in close. Do you perhaps have things like imported CAD maps in your model?

No cad maps.So the invisible picture plan is there, its not a glitch?

It’s called “image clipping” and I suppose you can call it a “glitch”. I don’t know enough of the tech side to explain the exact whys. Generally speaking in “perspective” mode you can get image clipping when your zooming in very close to objects in your model. In “parallel projection mode” It can occur even without zooming real close. From my experience it’s best to do most of your modeling in perspective mode. In my experience it’s not very often I need to model in parallel projection.

Thanks for the help and the knowledge!!!