2020 Rand McNally Road Atlas

[sprjus4]

Haven't seen it mentioned yet... I-69 is also now shown along the recently completed portion between Bloomington and Martinsville in Indiana.

[hobsini2]

Haven't seen it mentioned yet... I-69 is also now shown along the recently completed portion between Bloomington and Martinsville in Indiana.

Which is absolutely nice to drive on.

[midwesternroadguy]

But 1/500 is a smaller fraction than 1/200.  Therefore, zooming out is a reduction.

It's not viewed as a fraction (1/500), it's viewed as a relationship (1:500).  I'll take her word since she has a Ph. D. in geography.

[Rothman]

Ratio, fractions -- same thing.

[midwesternroadguy]

Ratio, fractions -- same thing.

Not really.  Do you have a Ph. D. in cartography?  As I said, I'll trust a professor's expertise over yours. 🙂🙂

[Rothman]

Ratio, fractions -- same thing.

Not really.  Do you have a Ph. D. in cartography?  As I said, I'll trust a professor's expertise over yours.

Suit yourself.

[PHLBOS]

While I was on vacation for the last two weeks, I purchased the 2020 atlas at Walmart.  One item not mentioned (& I'm not sure if the prior 2019 version showed such) was how the Mass Pike (I-90) is shown post-AET conversion... particularly the now-free sections in Springfield and south of Worcester.

In addition to the above (I-90 is now shown as free between Exits 4 & 7 as well as between Exits 10 & 11 (includes Exit 10A)); it also shows the stretch between MA 16 (Exit 16) and I-95/MA 128 (Exit 14/15) as a free highway.  If Exit 16 was a full/complete movement interchange, showing that short stretch as free would be correct; but since Exit 16 is a partial-movement interchange (westbound exit/eastbound entrance), that depiction is not correct... there's an AET gantry between Exits 16 & 17 with 17 being the next full-movement interchange east of I-95.  That short stretch should still be shown as a tolled facility.

[skluth]

But 1/500 is a smaller fraction than 1/200.  Therefore, zooming out is a reduction.

It's not viewed as a fraction (1/500), it's viewed as a relationship (1:500).  I'll take her word since she has a Ph. D. in geography.

As someone with just a BS in geography along with 28 years as a professional cartographer, they are most certainly viewed as fractions. A 1:500 scale is a smaller scale than a 1:200 scale in every textbook I've owned, because 1/500 is the smaller fraction just like Rothman stated. It's also a relationship. But that doesn't mean you're right. 

But don't take my word for it. Let's reference the Carto intro text from ESRI, who know a thing or two about cartography.

• Maps often are referred to as being "large scale" or "small scale". Oddly enough, a large scale map shows more detail than a small scale map, which confuses many people. If you think of scale in terms of fractions, however, this makes sense. The fraction 1/10,000 is larger than 1/25,000,000. Thus, a map at 1:10,000 would be a larger scale than a map at 1:25,000,000. There are no rules about what is considered large scale or small scale, but generally, 1:24,000 and larger is large scale and 1:250,000 and smaller is small scale.

There is no PhD in Geography who would claim 1:500 is bigger than 1:200. At least one who know what they were talking about. I think you misunderstood.

[bandit957]

Any map that's smaller than life size has to generalize features.

[skluth]

Any map that's smaller than life size has to generalize features.

That is correct. In map series (e.g., USGS topo maps) there is even a priority. I don't know what it is at USGS, but this is a spec example from my office (NGA, formerly DMA). (For the record, I'm retired.)

• Rivers and other bodies of water are placed as exactly as possible
• Railroads are offset at a distance to avoid overprinting
• Roads are offset from both Rivers and Railroads to avoid overprinting

Obviously, there is some cartographic judgment when collecting. These specs were all thrown out when we went from collecting for paper products to digital products when we changed to collecting centerline data. But making maps in densely featured areas (often, but not always urban) was always a challenge. When I was collecting maps, it was usually Topographic Line Map series (TLM 1:50k and 1:100K) and occasionally Joint Operation Graphics (1:250K). It was back when few people saw satellite imagery, so I loved my job looking at places all over the world. Nowadays everyone collects centerline data because good software can do the offset for you if needed.

[kphoger]

Any map that's smaller than life size has to generalize features.

I'm pretty sure you could map 1:2 accurately in every detail.

[skluth]

Any map that's smaller than life size has to generalize features.

I'm pretty sure you could map 1:2 accurately in every detail.

It's easier, but not necessarily true. It's a ridiculous scale for this exercise, but as soon as you start shrinking from 1:1 you quickly hit a point where at least something must be offset to avoid overprints, simplified for a variety of reasons, or even exaggerated for comprehension (this last happens more often that you think). Even at 1:1 it can be an issue. Let's say you are mapping a circuit board. There is no way to make it legible at scale. And don't forget labelling. Labels take space too. (As do legends and compass roses.) If there are no labels, you don't have a map; you have a scale model. Yes, you can put all your labels, legends, and north arrows on the margin. But then you need guide lines from the labels to their objects and it doesn't take many to create a serious legibility issue.

There are also issues where a decision must be made when items align vertically, e.g., wires along a power line. If you generalize and just say power line, you have lost accuracy. If you map every single line, how do you do it? You can create parallel lines, but now you've created some horizontal accuracy. In any case, converting a 3D world to a 2D map without even a minimal amount of accuracy lost is practically impossible.

There aren't many instances where a 1:2 map wouldn't be accurate. But it can still happen.