vector - How to calculate azimut & elevation relative to a camera direction of view in 3D ...? -

-

i'm rusty bit here.

i have vector (camdirectionx, camdirectiony, camdirectionz) represents camera direction of view. have (camx, camy, camz) camera position.

then, have object placed @ (objectx, objecty, objectz)

how can calculate, camera point of view, azimut & elevation of object ??

the first thing do, simplify problem, transform coordinate space camera @ (0, 0, 0) , pointing straight down 1 of axes (so direction (0, 0, 1)). translating camera @ (0, 0, 0) pretty trivial, won't go that. rotating camera direction (0, 0, 1) little trickier...

one way of doing construct full orthonormal basis of camera, stick in rotation matrix , apply it. "orthonormal basis" of camera fancy way of saying 3 vectors point forward, up, , right camera. should @ 90 degrees each other (which ortho bit means), , should of length 1 (which normal bit means).

you can these vectors bit of cross-product trickery: cross product of 2 vectors perpendicular (at 90 degrees) both.

to right-facing vector, can cross-product camera direction vector (0, 1, 0) (a vector pointing straight up). you'll need normalise vector out of cross-product.

to vector of camera, can cross product camera direction vector right-facing vector calculated. assuming both input vectors normalised, shouldn't need normalising.

we have orthonormal basis of camera. if stick these vectors rows of 3x3 matrix, rotation matrix transform our coordinate space camera pointing straight down 1 of axes (which 1 depends on order stick vectors in).

it's easy calculate azimuth , elevation of object.

to azimuth, atan2 on x/z coordinates of object.

to elevation, project object coordinates onto x/z plane (just set y coordinate 0), do:

acos(dot(normalise(object coordinates), normalise(projected coordinates)))

this give positive angle -- want negate if object's y coordinate less 0.

the code of like:

fwd = vec3(camdirectionx, camdirectiony, camdirectionz) cam = vec3(camx, camy, camz) obj = vec3(objectx, objecty, objectz)  # if fwd normalised can skip fwd = normalise(fwd)  # translate camera @ (0, 0, 0) obj -= cam  # calculate orthonormal basis of camera right = normalise(cross(fwd, (0, 1, 0))) = cross(right, fwd)  # rotate camera pointing straight down z axis # (this matrix multiplication) obj = vec3(dot(obj, right), dot(obj, up), dot(obj, fwd))  azimuth = atan2(obj.x, obj.z)  proj = vec3(obj.x, 0, obj.z) elevation = acos(dot(normalise(obj), normalise(proj))) if obj.y < 0:     elevation = -elevation

one thing watch out cross-product of original camera vector (0, 1, 0) return zero-length vector when camera facing straight or straight down. define orientation of camera, i've assumed it's "straight", doesn't mean when it's facing straight or down -- need rule.


Comments

Post a Comment

Popular posts from this blog

django - How can I change user group without delete record -

-
on website user have 1 group. , user can change group. it's made user.groups.clear() and user.groups.add(new_group) but it's not efficient, because there 2 sql query: delete, insert. how can change group update query? user , group related each other using manytomanyfield . means intersection table exists relating both entities, , if don't specify model map (using through attribute) django creates 1 you. looking @ sources django.contrib.auth.models see that's case. fortunatly, can access intermediary model using through attribute of manager (in case, user.groups.through ). can use regular model. example: >>> alice = user.objects.create_user('alice', 'alice@example.com', 'alicepw') >>> employee = group.objects.create(name='employee') >>> manager = group.objects.create(name='manager') >>> alice.groups.add(employee) >>> alice.groups.all() [<group: employee...
Read more

java - Need to add SOAP security token -

-
i need set custom soap header attribute on jax-ws generated webservice client. case webservice calls must go through proxy server requiring specific token (recieved web request header) present in soap request header. e.g.: 1 carserviceservice service = null; 2 service = new carserviceservice(new url(url), new qname(qname); 3 carserviceendpoint port = service.getcarserviceport(); it seems in line 3 wsdl retrieved , call fails due missing security token. 1 point direction on how done? a detailed example has been mentioned here: creating , deploying jax-ws web service on tomcat 6 this article shows how create , use security token .
Read more

java - EclipseLink JPA Object is not a known entity type -

-
i have strange problem eclipselink , object want persist. have 1 object (keypointlistimpl) stores object keypointimpl in list. persisting keypointimpl objects works great if try persist keypointlistimpl object java.lang.illegalargumentexception says object keypointimpl isn't known entity type. here keypointimpl code: @entity @table(name="keypoints") public class keypointimpl implements keypoint { @id @generatedvalue(strategy = generationtype.identity) private int id; @enumerated(enumtype.string) private detectortype keypointtype; private float x; private float y; private float size; private float angle; private float response; private int octave; private int classid; ... } here keypointlistimpl code: @entity @table(name="keypointlists") public class keypointlistimpl implements keypointlist { @id @generatedvalue(strategy = generationtype.identity) private int id; @onetoone(cascade={ca...
Read more