Problem with the model : it looks like z-fighting

I generated this model using Qgis and Spirix pluging to model a big part of a city. the problem is that the model doesn’t look good. It looks like there is z-fighting but i checked each extruded element and there isn’t. I’ve read there is a fix by editting the camera. any one can help ?

At a guess without seeing anything, you should either attach the model or at the very least a screenshot, your model is somehow located a long way from the Sketchup Origin.