depth shading

[Koma]

Can anyone explain why the depth shading isn't available on all the lakes? It can't be because they haven't been surveyed because I have a large lake that I can't use it on and a very small farm pond that you can?

[jrfuda]

I was wondering the same thing. My guess is that the contour lines on these lakes without depth shading are just an image whereas there is significantly more data needed to support depth shading since it actually has a depth value for every pixel on the map. The fact that my depth shading colors never perfectly align with the contour lines likely confirms this theory.

I agree that there seems to be no rhyme or reason to which lakes have not depth shading. We have several park lakes - really big ponds - that have depth shading in town, but a couple of much larger lakes that are very popular for fishing have contour lines but no depth shading.

[Koma]

I was wondering the same thing. My guess is that the contour lines on these lakes without depth shading are just an image whereas there is significantly more data needed to support depth shading since it actually has a depth value for every pixel on the map. The fact that my depth shading colors never perfectly align with the contour lines likely confirms this theory.

I agree that there seems to be no rhyme or reason to which lakes have not depth shading. We have several park lakes - really big ponds - that have depth shading in town, but a couple of much larger lakes that are very popular for fishing have contour lines but no depth shading.

Yea the lake I’m talking about has contour lines, definitely not accurate but fairly close. I guess my thinking is that depth shading is set by the user so if the lake has contour lines it should show depth shading to those lines? The small lake (pond) around me that does show depth shading has contour lines but not nearly as many. Just seems really odd

[ifishinxs]

My lakes are not mapped at all. So I mapped them myself and also did the color shading.

[jrfuda]

I guess my thinking is that depth shading is set by the user so if the lake has contour lines it should show depth shading to those lines? The small lake (pond) around me that does show depth shading has contour lines but not nearly as many. Just seems really odd

It does seem odd, but a key thing to remember is most of what you see on Garmin charts are just images. The charting device cannot interpret what the image means without additional data. It would be like trying to figure out how tall a mountain is based on a photo of the mountain. Even with Garmin's premium Lake View Ultra charts, most of the cool stuff are just images overlayed at various transparency settings. The data needed to do depth and shallow shading, auto routing, fish eye and marine eye views, etc is in addition to the static images. For the lakes with dynamic lake level, there is even more data because the chart has to dynamically draw the contours based on the day's offset. For things like auto routing it's even more data required because the chart has to know depth, hazards, and bridge heights - all of which can't be stored in a static image.

As ifishinxs said - recording QuickDraw contours is the best workaround you have. Like you, I've fished several lakes that had contour lines but no shading, or were nothing but a blue blob on the maps. Fortunately, most of these were small enough that I was able to completely map them out. Bad thing is you have to put a lot of work in, especially if the lake is large.