Junction Views for Garmin On The Road Devices - Which Junctions are displayed?
For several years now, Garmin's City Navigator North America maps offer Junction Views on many of the On The Road devices. There has been a lot of discussion and guessing as to the various Garmin devices' differences in the number of Views displayed. Much of the discussion and guesses have been based on common sense conclusions based upon some real life experiences as well as file sizes of the Junction View file but little testing and reporting of Junction Views has been posted to date as this FAQ is begun in October 2015.
I have tested three Garmin nuvis on a route and gotten some surprising results that challenge our commonly held beliefs. I share the results below. This test is quite limited in devices tested and extremely limited in test routes so I encourage others to conduct their own tests and share their results. For your test results to be included in this FAQ, please post your tests, comments, corrections, etc. in the following thread:
Using the different nuvi models, each with the current 2016.20 map update, latest firmware, and default JCV files supplied by Garmin as part of the map update, I simulated a route along the interstate from one to the other side of Flagstaff AZ, then a return home. The models tested are the nuvi 3597, the 2460, and the 855.
Interchanges and exit ramps along the route: I-17 Exit 340A; I-40 Exit 201; and a challenging double-ramp on I-40: Exit 195 followed immediately by the unnumbered AZ-89 North exit. A table follows with my JV results:
Exit - 3597 - 2460 - 855
340A - JV* - JV - No JV
201 - JV - No JV - JV
AZ-89 - JV** - JV** - No JV
Results: There are a couple results seen here that I found unexpected and I imagine will be unexpected by many others here at The Factory.
Expected: The nuvi 3597 shows all three split-screen JVs. The asterisk refers to an added Birds Eye View JV and the double asterisk indicates that the double ramp does not show a JV for Exit 195 but does show a JV for the AZ-89 North ramp.
Unexpected: It has been assumed here that the nuvi 2460 would offer the identical results as the 3597 with the exception of not having the added Birds Eye JV. This test shows the assumption to be wrong—the 2460 does not offer a JV for the ramp at Exit 201. This is not a one-time 2460 fluke—I've not seen a JV at Exit 201 many times and with more than a few map updates.
Expected and really unexpected: The nuvi 855 with its tiny default JCV file does not offer a JV for Interchange 340A and AZ-89 (expected since the JCV file offers so few JVs) but does show a JV for Exit 201 (really unexpected since it's offering a JV not available with the split-screen nuvi 2460 which has been assumed to show all available JVs!)
1) Contrary to popular thought here, not all nuvi models with split-screen JCV files show the same number of JVs. The split-screen JCV with the 2460 does not offer the Ramp I-40 Exit 201 while the 3597 does offer a JV there.
2) Although the nuvi 855 with its tiny JCV file shows fewer JVs as expected with its small filesize, it unexpectedly does show a JV at Exits where at least one nuvi, the 2460 with a larger JCV file, does not show a JV.
3) Maybe the oddest result is that for both the 2016.10 and 2016.20 maps, the respective JCV files for the split-screen 2460 and 3597 are identical in size for the 2016.10 update and again for the 2016.20 update, yet the 2460 does not show all the JVs that the 3597 does. This may imply that in addition to the data of JVs offered within the JCV file, the nuvi's decision of whether to display or not display a given JV is also controlled by each device's firmware or other software/hardware component unrelated to the map file and JCV file data contents. Also somewhat surprising is that the split-screen JCV file size remains constant between nuvis that offer just regular JVs as well as nuvis that offer regular, Birds Eye and Active Lane Guidance, using the 2460 and 3597 models as examples. If Birds Eye and Active Lane Guidance are built into the JCV file, the devices that can't display these simply ignore the data—or maybe the Birds Eye and Active Lane Guidance are offered in yet another file other than the jcv file.
For those of us with newer-than-ancient Garmin On The Road, we all know what the standard Junction View image looks like. For folks moving up to a newer device that offers Birdseye views and Active Lane Guidance, here are examples of what these will look like:
Birdseye and standard PhotoReal JV:
Active lane Guidance:
Update: from tests done by alandb and myself on 8/17/2016, it appears that regular Junction Views and Birdseye JVs are built into the jcv file offered with each map update but that the Active Lane Guidance data is in another file, maybe the .img map file or maybe some other file.
CraigW - Aug 18, 2016
Added YouTube links to show Birdseye view and Active Lane Guidance
CraigW - Aug 17, 2016
Info provided for where Birdseye JV data is stored and where Active Lane Guidance is not stored