Guidance on AT filesize for specific platforms

[archjeb]

This is more a curiosity question.

At what point does the file size create issues on specific platforms?

In other words, I have an HDS Pro and a mix of HDS Live units.
But on another boat, maybe an HDS Gen3.

At what point does the files become too big for the Gen3 so that its sluggish? How about for a Carbon? Or even the Live?

When I use Zlib compression for my Raster images, the AT file size gets reduced. But what does that exactly mean for the MFD? Does it mean that the MFD has to uncompress the entire file when you zoom in and out? Or does it cache the files after it uncompresses them? At what point does the file size get too large where the cache is full?

[fjordfischer]

I recommend that you sign up to the beta group, because many things are explained there.

With each new device class, the computing power (processor, RAM) increases.

I have never experienced AT5 reaching its real limits with HDS, but all devices can be slowed down with complex data, even the newest ones.

The SD card size is a limiting factor for raster data. Consequently, you cannot really display large areas with rasters at high resolution/zoom.

With vector data, you can map entire, large countries/continents (e.g. Norway approx. 1 GB).

But it is the same for all AT5s: The device pulls a maximum of 4 cells (if I remember correctly) from the AT5 data set and displays them, loading new cells when leaving cells spatially or zooming to other levels. So the reading speed of the SD card plays a role, and of course also the amount of data the device has to search through.

You can increase the time it takes to reload cells to several seconds by using complex representations: many lines and/or points, many labels, many polygons with different colors, etc.

I take this into account, for example, by using thematic maps of the same areas:
- pure depth maps with navigation marks for normal use when fishing
- the same map complete with depth points, wrecks, land names, possibly with land as an aerial photo grid to look up for additional information
- the pure depth maps with navigation marks with older fishing points for better orientation at the fishing spot
- etc.

The fastest would still be the first thematic map, without all the others on the SD card - also an option.