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Subject: Re: [emergency] Re: Actually CAP but was Circle and Polygon
Sounds like a plan for the CAP Issue list. Thanks Carl > Carl, if you don't mind I'd like to keep this on the issue list for > the time being... as you point out, it has a political aspect, so I'm > thinking it'll be especially important that we've made sure > everyone's had a chance to weigh it carefully and that we've come > away with a quorum decision. > > Thanks! > > - Art > > > On Jun 15, 2005, at 6/15/05 11:48 AM, Carl Reed wrote: > >> Well stated. >> >> Thanks Art - >> >> I stand corrected. I also spoke with another implementor of CAP on the >> same issue of the CRS and withdraw any suggestions of not having WGS >> as >> mandatory. >> Cheers >> >> Carl >> >> >>> Carl - >>> >>> If the primary purpose of the circles and polygons in CAP was to >>> provide data for GIS display I'd have an easier time with your >>> suggestion. But that's not really the case. >>> >>> The primary purpose of the geospatial elements in CAP is to enable >>> location-aware receivers to identify those messages that are relevant >>> at their locations or at other locations of interest... or, depending >>> on network architecture, to enable routing mechanisms to make those >>> determinations on the end-receivers' behalf. So we're talking about >>> devices that don't need to, and in many cases can't, support >>> conversions among multiple reference systems. >>> >>> As you point out, the geospatial systems that need transformations >>> from WGS-84 to other CRSs are generally able to do them themselves, >>> as well as being able to take advantage of even more detailed GML >>> data that might be included as a resource. But there's a larger >>> universe of devices out there, at both the input and output ends and >>> even in the middle, for which cost, weight, power, traffic volume and >>> other constraints suggest a simpler approach. >>> >>> So... again, speaking as just one of the TC membership... I hesitate >>> to complicate the CAP format, which has been used successfully even >>> in Australia, unless we're shown an absolute technical need to do >>> so. >>> Right now the issue seems to be one of local preferences, and >>> we're >>> never going to be able to please everyone. >>> >>> - Art >>> >>> >>> On Jun 15, 2005, at 6/15/05 11:04 AM, Carl Reed wrote: >>> >>> >>>> Art - >>>> >>>> Thanks for the quick response. >>>> >>>> Just to clarify so that there is no misunderstanding: >>>> >>>> 1. I agree that specifying WGS 84 as the default CRS and best >>>> practice is >>>> a good thing. There is no disagreement here.2. The current CAP 1.0 >>>> spec references the EPSG definition of WGS 84. This >>>> is a good thing.3. The current approach works within the contextual >>>> framework of those who >>>> have implemented CAP to date. Fine >>>> That said, please consider: >>>> >>>> 4. I am not asking to change this position. >>>> 5. I am asking for the ability to specify another CRS. >>>> 6. This does not add complexity - nor does it break >>>> interoperability. >>>> 7. It actually enhances interoperability as ALL >>>> communities/nations/jurisdictions are accommodated.8. It does not >>>> break interoperability because the optional element >>>> provides the EPSG code for the CRS being used. The majority of >>>> geospatial >>>> technology providers know of and use these codes.9. Most systems >>>> ingesting a WGS 84 based CAP payload will have to >>>> transform any coordinates contained in the CAP message into some >>>> other >>>> projected system, such as State Plane. This is necessary to >>>> display/portray the location of an alert in the context of a common >>>> operational picture. >>>> I am looking toward future usage and flexibility. >>>> >>>> If my position falls short and is unacceptable, I will give up >>>> pushing >>>> this position WRT CRS extensibility for CAP and move to other EM TC >>>> actions and work. >>>> >>>> >>>> >>>> >>>>> [Oops, our notes passed each other in the mail.] >>>>> >>>>> On Jun 15, 2005, at 6/15/05 9:42 AM, Carl Reed wrote: >>>>> >>>>> >>>>>> You still appear to be missing the point. We can leave CAP and >>>>>> EDXL >>>>>> with >>>>>> WGS 84 as the default (but not mandatory!) so that all existing >>>>>> implementations work and the level of "simplicity" being sought is >>>>>> maintained. We are suggesting optional elements that would allow >>>>>> folks to >>>>>> use other than WGS 84 as the only CRS. >>>>>> >>>>>> >>>>> >>>>> OK, my mistake... guess we *aren't* all agreed on the need to fix >>>>> on >>>>> a single standard reference system. Personally, I think we do, if >>>>> only in order to keep things simple for implementers. Otherwise >>>>> we're going to have only local rather than global >>>>> interoperability of >>>>> CAP messages. >>>>> >>>>> What we're not getting here is a sense of proportion. Is this a >>>>> serious and widespread problem or just a few folks' personal >>>>> theoretical axe? I really can't tell... although I'll note again >>>>> that none of these complaints seem to come from folks who've >>>>> actually >>>>> deployed implementations. >>>>> >>>>> - Art >>>>> >>>>> ------------------------------------------------------------------- >>>>> -- >>>>> To unsubscribe from this mail list, you must leave the OASIS TC >>>>> that >>>>> generates this mail. You may a link to this group and all >>>>> your TCs >>>>> in >>>>> OASIS at: >>>>> https://www.oasis-open.org/apps/org/workgroup/portal/ >>>>> my_workgroups.php >>>>> >>>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> --------------------------------------------------------------------- >>> To unsubscribe from this mail list, you must leave the OASIS TC that >>> generates this mail. You may a link to this group and all your TCs >>> in >>> OASIS at: >>> https://www.oasis-open.org/apps/org/workgroup/portal/ >>> my_workgroups.php >>> >> >> >> >> > > > --------------------------------------------------------------------- > To unsubscribe from this mail list, you must leave the OASIS TC that > generates this mail. You may a link to this group and all your TCs in > OASIS at: > https://www.oasis-open.org/apps/org/workgroup/portal/my_workgroups.php
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