Frame--
Resolution Unit: This popup allows you to select how the rendered frame's image size is specified, either as pixels, or as inches.
Frame Width/Height: With Frame 'Width' and 'Height', the user can specify the size of the frame rendered when you invoke the 'Render' command. Dependant upon the resolution unit, if 'Pixels' is selected, then you can specify the size in pixel units, or if 'Inches' is specified, the user can specify the printed resolution of the rendered image in inches. When set to 'Inches', the DPI setting is used to determine the number of pixels rendered. The typical video size of 640 pixels by 480 pixels is the default size.
DPI: The DPI input field allows the user to directly determine the number of "Dots Per Inch". This is particularly useful when defining image height and width using the 'Inches' resolution unit, as it will be used to determine the final pixel resolution of the rendered images. It will also be added to files on export determining the eventual printed size of the image.
Pixel Aspect Ratio: Most computer screens, by default, use a 'Pixel Aspect Ratio' of 1 which yields "square pixels", what most people are used to. However, some target media use non-square pixels to display images such as NTSC television (0.90). Use this setting to properly render the image for its intended destination. Note: modo will still display the image as if they were square pixels, so rendered images will look squashed/stretched depending on this setting.