Your syllable-by-syllable foot-by-foot scanning does work, and you show you know the “rules” and can do it successfully. However, it’s well worth noting the internal structure of the dactylic hexameter line, which never (well, hardly ever) falls into two exact halves. That is to say, you don’t find word-end at the end of the 3rd foot; the line is swept clear over its midpoint. Verses do tend to be bipartite, but word-division tends to fall within the 3rd foot (and/or occasionally within the 4th). That’s what’s known as the caesura.
When learning to read metrically—which will add immeasurably to your enjoyment—it can be useful to aim for the caesura, which most often comes after the first (long) syllable of the 3rd foot. In this particular verse, for instance, the caesura comes at ter circ(um) Iliacos |, LONG long LONG short-short LONG. The line breaks there. You’ll find that the next line has the same pattern, exanimumqu(e) auro |. The individual feet may not have exactly the same syllabic structure (spondees/dactyls: here LONG short-short LONG long LONG) but in both lines the breakpoint between the two parts of the line comes exactly at the same place, two-and-a-half feet into the line, after the third LONG. Following that of course you will have either a long or a double-short before you hit the LONG that kicks off the 4th foot, and then you’re within reach of the 5th+6th feet “shave and a hair-cut” clausula. Once you get the basic rhythm fixed in your head you’ll find that verses effectively scan themselves, without your having to go through the laborious process of working out the length of each individual syllable.
Of course, that may take a while, and the better you know your vowel quantities irrespective of meter (e.g. the second a of raptaverat must be long, and the e must be short), the less likely you are to go wrong. Ilium always starts long-short, and the –acus ending has short a. (It’s a greek formation, Ιλιακος. Ovid loves greek names and their forms, taking over many of them from hellenistic greek literature.) But I really would encourage you to try reading whole lines, with the caesura to help steer you through, along with closing “shave and a hair cut” (sometimes called the adonic section, after Ω τον Αδωνιν), and the basic dactylic rhythm controlling it all. Before tackling complete lines you might like to look through a bunch of consecutive lines and (1) get as far as the 3rd-foot caesura (not all lines have it directly after the longum: some have it after the following short, i.e. within the second half of the foot); and then (2) identify the closing adonic section of each line (most often in the dactyl-spondee form, but just occasionally with a spondee instead of the dactyl, making the line feel heavy); and then, only then, (3) bridge the remaining gap (end of 3rd foot and all of 4th) between caesura and clausula. A minority of lines, you might see, sweep right over the 3rd foot with a longer word that runs into the 4th (not stopping at the end of the 3rd, mind), resulting in a 4th-foot caesura, but you won’t find too many of them.
I think this will engender an appreciation of the dynamics of the hexameter right from the start, as well as simply making it easier to read metrically. And the verbal structure complements the metrical. The relationship between the words (and syntax) and the meter is the most fascinating thing about latin versification; it goes to the very essence of verse. Qimmik pointed out Iliacos at caesura picked up by its noun muros at verse end, an aesthetically satisfying pattern which recurs again and again in Ovid and other poets, and is something of a mannerism in the pentameter of elegiacs. The adjective (or adjectives) routinely comes in the first half, which sets things up for its resolution in the form of its noun in the second; so the main syntax tends to be concentrated in the latter part of the line. Cf. your second line here, adj. (exanimum) kicking off the first half, its noun (corpus) kicking off the second (rather than being postponed to the end of the line, another favored pattern, a sandwich). Similarly the adverbial stuff, ter and auro, in the first halves, have to wait for their verbs in the second halves. And there’s so much more. In Ovid it can come to seem glib and mechanical, especially when each line is complete in itself as here, but it never loses its effect, and he can ring many changes, and he can ring many changes. There’s no-one more fluent as a versifier, just as there’s no one more ingenious in “inventio.” But the supeme master of the dactylic hexameter is the endlessly supple Virgil.
EDIT: This before seeing your and Q’s second posts, so forgive repetition.