Convert .tiff to .dwg

How can i convert a large +1gb .tiff to .dwg format? should i use autocad or GIS? cause in Arcgis cannot export tiff to dwg just some picture formats.

We use Civil3d. I import the tiff using the world file to align it automatically.

Using MAPWSPACE to get the DATA CONNECT dialog box, I use the insert raster image.and I navigate to the folder with the tiff file and the world file. Then CONNECT,  and Show on map.  The orthomosaic will now be at the coordinates used by Pix4d. We use a state plane coordinate system to process the original photos with Pix4d.  Whatever system you use has to be assigned in Civil3d before trying to insert the image.

We use the same system in Traverse PC, a surveying drafting program except that the image and project file have to be converted to a jpeg.  Pix4d has instructions available on how to do this.

Rick Miller