In this lesson we'll discuss scale dependency and projections. 

AWIPS-2 allows you to load data on any scale and be able to switch back and forth between scales and maintain the data being displayed. Let's first discuss how projections and scales affect the display of radar data. Let's start off by loading a digital vil product on the CONUSscale. So let's go to the scale menu to make sure we're on the CONUS scale. And if not, select CONUS. Next let's go to the kcri menu. Then go down to derived products, then over and up to digital vil and let's go ahead and load that one in. Next, use the mouse scroll wheel to zoom in on the state of Oklahoma. And let's target the storm north of the radar site, this one. So let's zoom in further on it. And notice the orientation of the county boundaries. Well this county boundary seems to be oriented vertically from north to south. How about the data? Well the data seems to be skewed a little bit to the northeast, so it's oriented in a northeast to southwest direction. 

Okay, let's go ahead and change the scale from CONUS to North American and observe what happens. So go to the scale menu and select North American. Next let's zoom back in on Oklahoma and let's zoom back in on that storm north of the radar site. So what difference do you see? Well the state and county boundary seems to have been skewed to the left, along with the data. So the data is now in a vertical direction. So why is that? Well the North American scale uses a polar stereographic projection while the CONUS scale uses a lambert conformal conic projection. So what happens is the D2D perspective reproject data on the new scale. Now your ITO may configure projection settings for different map scales for your local site. As a best practice tip, try to avoid loading radar data on larger scales like the North American or in Northern Hemispheric due to the projection changes you just witnessed here. 

Next let's see how scales affect the display of satellite data. Now before we go on let's go ahead and clear our display. Go up to clear. And let's go ahead and load a satellite product on the State scale. So let's go to the scales menu and select States. And next let's go to the satellite menu and select the first one - IR window. Okay now that we've done that, let's go ahead and increase our scale from State to North American. So let's try that. Go to the scale menu and select North American. Let's see what happens. What do you see? Well it looks like we have satellite data missing from the west coast - California, Washington, Oregon and the Eastern Pacific. So why is that? Well before we talk about why let's go ahead and actually load the satellite data directly on the North American scale. 

So to do that, let's just clear our display. Go up to clear. And on the same North American scale let's reload our satellite data. Go to satellite and select the same product - IR window. So as you see we have complete satellite coverage. The West Coast and Eastern Pacific now has satellite data. So why is that? Well, when loaded on a large scale, data from multiple satellites need to be stitched together to display on the entire domain. So when you switch scales from small to large, it's recommended that you clear the data and reload, just as we did here.