SketchUp High Resolution Images
To create High Resolution images from SketchUp, use a rendering engine such as IRender nXt and choose the resolution desired. IRender nXt can Render at any resolution or render quality desired.
By default, SketchUp exports 2D images at the view size (the current size of the SketchUp window) and at 72 pixels per inch (PPI).
Using IRender nXt, you can render a high-quality, high-resolution image suitable for creating posters, etc.
See: IRender Render Tab to set the resolution of the output image.